According to Srila Bhaktivinoda Thakur, said in his Sri Chaitanya Shikshamrita 3.2., there are two categories of Vaishnavas, namely Ordinary Vaishnavas and Transcendentally Situated Vaishnavas (also quoted in Pancharatra-pradipa. section on Serving the Vaishnavas - Vaishnava seva.).

The ordinary Vaishnavas are of three categories (1) those who believe in the philosophy of Krishna consciousness but do not practice strictly, (2) those who accept the markings of a Vaishnava and respect the Vaishnavas but do not practice strictly themselves, (3) and those who are from Vaishnava families and wear the marks of a Vaishnava but do not practice strictly. In India one can readily see examples of these three classes of ordinary Vaishnavas, as one can with the generations of Gurukulis and congregational devotees in the west. They can all be elevated by associating with more committed Vaishnavas.

The three categories of transcendentally situated Vaishnavas begin at the kanistha stage and are as follows (1) those advanced being fixed in following the regulative principles, and by regularly chanting (the kanistha adhikaris) (2) those advanced in faith and practices are known as madhyama adhikaris and (3) those who are actually advanced in realisation of Krishna - uttama adhikaris.

Although all Vaishnavas (devotees of the Lord), there's a world of difference in habit, intent, and realisation of these two kinds (the ordinary and the transcendental).

"The root cause of devotional service to Lord Krishna is association with advanced devotees. Even when one's dormant love for Krishna awakens, association with devotees is still most essential." [Chaitanya Charitamrita. Madhya 22.83]

The sages of Naimishranya further point out:
"The value of a moment's association with the devotee of the Lord cannot even be compared to the attainment of heavenly planets or liberation from matter, and what to speak of worldly benedictions in the form of material prosperity, which are for those who are meant for death." [Srimad Bhagavatam. 1.18.13]

Srila A.C. Bhaktivedanta Swami Prabhupada writes:
"Srila Jiva Gosvami, in his thesis Bhakti-sandarbha (202), has stated that uncontaminated devotional service is the objective of pure Vaishnavas and that one has to execute such service in the association of other devotees. By associating with devotees of Lord Krishna, one develops a sense of Krishna consciousness and thus becomes inclined toward the loving service of the Lord. This is the process of approaching the Supreme Lord by gradual appreciation in devotional service. If one desires unalloyed devotional service, one must associate with devotees of Sri Krishna, for by such association only can a conditioned soul achieve a taste for transcendental love and thus revive his eternal relation with Godhead in a specific manifestation and in terms of the specific transcendental mellows (rasa) that one has eternally inherent in him. [Chaitanya Charitamrita Adi 1.35, purport).

The Lord's temple is where Vaishnavas congregate and worship the Deity together. Just as you should serve the holy name and hear the Srimad-Bhagavatam in the association of devotees, you should worship the Deity in their association, for the Lord takes pleasure in seeing His devotees co-operate in His service.*

*In elaborate puja, such as offering expanded services to the Salagram sila, there is scope for two, three, or four devotees to worship together, each devotee concentrating on specific aspects of the service.

Vaishnava Character Is Cultivated Through Deity Worship
In his Chaitanya-charitamrta (Madhya 22.75), Srila Krishnadasa Kaviraja Gosvami says, ``A Vaishnava is one who has developed all good transcendental qualities. All the good qualities of Krishna gradually develop in Krishna's devotees."

And in the Srimad-Bhagavatam (5.18.12) Prahlada Maharaja says:
In one who has unflinching devotional faith in Krishna, all the good qualities of Krishna and the demigods are consistently manifest. However, he who has no devotion to the Supreme Personality of Godhead has no good qualifications because he is engaged by mental concoction in material existence, which is the external feature of the Lord. [quoted from Chaitanya-charitamrta. Madhya 22.76]
Lord Kapila describes devotees as follows: "The symptoms of a s€dhu are that he is tolerant, merciful and friendly to all living entities. He has no enemies, he is peaceful, he abides by the scriptures, and all his characteristics are sublime" (Srimad Bhagavatam. 3.25.21).
A devotee who properly worships the Deity naturally develops brahminical qualities, which in turn help him develop the twenty-six qualities of a Vaishnava. (See Chaitanya-charitamrta Madhya 22.78---80 for a list of these twenty-six qualities.)

In this regard Srila Prabhupada writes,
I am very glad to learn the practical result of Deity worship in your behavior. . . Deity worship is the practical demonstration, and hearing from the Spiritual Master is the nourishment of the idea. Krishna Consciousness is so nice that anyone who has a little taste of it must feel a distinction between his past and present life. [letter from Srila Prabhupada, 27 December 1968]

The Chaitanya-charitamrta (Madhya 13.139) describes the result of Deity worship this way:
A devotee constantly engaged in Deity worship according to the rules and regulations laid down in the Shastras and given by the spiritual master realizes gradually that he is in direct contact with the Supreme Personality of Godhead. Thus he loses all interest in so-called meditation, yoga practice, and mental speculation.

Ordinary Vaishnavas
A Vaishnava is distinguished from a non-Vaishnava by his indifference to anything other than Lord Krishna and His service.The more a devotee develops this quality, the more advanced he is.

In his Sri Chaitanya-Shikshamrita (3.2), Srila Bhaktivinoda Thakura describes devotees of varying grades:
Broadly speaking there are two categories of Vaishnavas, namely ordinary Vaishnavas and transcendentally situated Vaishnavas.

The ordinary Vaishnavas are of three classes: those who believe in the philosophy of Krishna consciousness but do not practice strictly, those who accept the markings of a Vaishnava and respect the Vaishnavas but do not practice strictly themselves, and those who are from Vaishnava families and wear the marks of a Vaishnava but do not practice strictly.
In India one can readily see examples of these three classes of ordinary Vaishnavas. They can be elevated by associating with transcendentally situated devotees.

Three Categories of Transcendentally Situated Vaishnavas
Transcendentally situated Vaishnavas belong to one of three categories, depending on their advancement in terms of chanting the holy name, degree of faith, and realization of the Supreme Personality of Godhead.

1. Advancement in Chanting
In the Chaitanya-charitamrita (Madhya 16.72) Lord Chaitanya defines an essential characteristic of the madhyama-adhikari:
A person who is always chanting the holy name of the Lord is to be considered [an advanced] Vaishnava, and your duty is to serve his lotus feet." Citing Srila Bhaktisiddhanta Sarasvati in his purport to this verse, Srila Prabhupada writes, "A neophyte devotee simply tries to chant the holy name, whereas the advanced devotee is accustomed to chanting and takes pleasure in it. Such an advanced devotee is called madhyama-bhagavata, which indicates that he has attained the intermediate stage between the neophyte and the perfect devotee.

Two verses later, Lord Chaitanya describes the uttama-adhikari:
A first-class Vaishnava is he whose very presence makes others chant the holy name of Krishna.

2. Advancement in Faith
Srila Rupa Gosvami distinguishes among three levels of spiritual advancement in terms of degrees of faith:
One whose faith is not very strong, who is just beginning, should be considered a neophyte devotee. [Bhakti-rasamrita-sindhu 1.2.19, quoted in Chaitanya-charitamrita Madhya 22.70]  He who does not know scriptural argument very well but who has firm faith is called an intermediate, or second-class, devotee. [Bhakti rasamrita-sindhu. 1.2.18, quoted in Chaitanya-charitamrita. Madhya 22.68]

One who is expert in logic and understanding of revealed scriptures, and who always has firm conviction and deep faith that is not blind, is to be considered a topmost devotee in devotional service. [Bhakti rasamrita-sindhu. 1.2.17, quoted in Cc. Madhya 222.66]

3. Advancement via Realization of Krishna
In the Srimad-Bhagavatam (11.2.47) there is a description of the third-, second- and first-class devotees in terms of their realization of Krishna:
A prakata, or materialistic devotee, does not purposefully study the shastra and try to understand the actual standard of pure devotional service. Consequently he does not show proper respect to advanced devotees. He may, however, follow the regulative principles learned from his spiritual master or from his family who worships the Deity. He is to be considered on the material platform, although he is trying to advance in devotional service. Such a person is a bhakta-praya [neophyte devotee], or bhaktabhasa, for he is a little enlightened by Vaishnava philosophy. But one who does not show proper respect to the devotees and to others is known as a materialistic devotee. [Srimad Bhagavatam. 11.2.47, quoted in Cc. Madhya 22.74]

An intermediate, second-class devotee shows love for the Supreme Personality of Godhead, is friendly to all devotees and is very merciful to neophytes and ignorant people. The intermediate devotee neglects those who are envious of devotional service. [Srimad Bhagavatam. 11.2.46, quoted in Cc. Madhya 22.73]
A person advanced in devotional service sees within everything the soul of souls, the Supreme Personality of Godhead, Sri Krishna. Consequently he always sees the form of the Supreme Personality of Godhead as the cause of all causes and understands that all things are situated in Him. [Srimad Bhagavatam. 11.2.45, quoted in Cc. Madhya 22.72]

Kinds of Vaishnava Association
How you associate with other Vaishnavas will depend on your and their level of advancement. A Vaishnava is cautious not to overestimate his own advancement or underestimate that of other Vaishnavas.

Association for Neophyte Devotees (kanishtha-adhikaris)
Since he cannot tell which devotees are advanced and which are not, the neophyte must simply take shelter of his spiritual master with faith and follow the rules and regulations to the best of his ability, learning from the spiritual master how to respect all Vaishnavas. By the mercy of the spiritual master, the neophyte can advance to the intermediate stage.

Association of Intermediate Devotees (madhyama-adhikaris)
The devotee on the intermediate level can distinguish between the different types of devotees. Thus, as stated in the above Bhagavatam verse, he relates to them in the proper way so as to advance in sadhana-bhakti. Toward less advanced devotees he should show compassion; toward his equals he should show friendship; and to superior devotees he should offer all respect and services and hear their instructions submissively. He avoids the nondevotees.
The pure devotee should execute devotional service by giving the greatest respect to the spiritual master and the acharyas. He should be compassionate to the poor and make friendship with persons who are his equals, but all his activities should be executed under regulation and with control of the senses. [Srimad Bhagavatam. 3.29.17]

Srila Prabhupada writes:
It is advised that an advanced devotee should be tolerant; he should show complete mercy to persons who are ignorant or innocent. A preacher devotee is meant to show mercy to innocent persons, whom he can elevate to devotional service. . . .As for a devotee's treatment of other devotees who are his equals, he should maintain friendship with them. His general view should be to see every living entity as part of the Supreme Lord . . . [A] saintly person is always tolerant and merciful, he is a friend to everyone, never an enemy to anyone, and he is peaceful. [Srimad Bhagavatam. 4.11.13, purport]
Thus the madhyama-adhikari should respect sincere but less advanced devotees and instruct them in devotional service. As for his equals--other intermediate devotees--he should live alongside them, take prasada with them, chant the Lord's name with them, and share with them his realizations of Krishna. He should always be straightforward, respectful, and friendly. (Text 5 of The Nectar of Instruction aptly describes these exchanges.)
When associating with an advanced Vaishnava, the intermediate devotee should very respectfully offer him all kinds of services and worship him to the best of his ability. Most importantly, when in the association of an advanced devotee one should practice the devotional anga of Shravana--very attentively hearing him speak on the Srimad Bhagavatam.

The Nectar of Instruction (5) further illustrates these points:
One should mentally honor the devotee who chants the holy name of Lord Krishna [the kanishtha-adhikari], one should offer humble obeisances to the devotee who has undergone spiritual initiation and is engaged in worshiping the Deity [the madhyama-adhikari], and one should associate with and faithfully serve that pure devotee who is advanced in undeviated devotional service and whose heart is completely devoid of the propensity to criticize others [the uttama-adhikari].

Association of Advanced Devotees (uttama-adhikari)
Since pure devotees are beyond sadhana-bhakti, they need not follow the rules of respect to advance. Still, by nature a pure devotee sees everyone as a devotee of the Lord, and thus internally he respects all. For practical purposes, he may externally make distinctions between devotees and nondevotees. .

Service to Vaishnavas
There are four basic ways to serve a Vaishnava: giving him a seat (reception), washing his feet (respect), hearing from him (association), and assisting him in any way (practical service). A devotee should offer these services to his spiritual master or to similarly advanced Vaishnavas.

The transcendentally situated Vaishnava is most advanced in spiritual knowledge, and therefore he is most deserving of respect, reception, service, and worship, regardless of his varna, ashrama, age, or other external condition. Serving the Vaishnavas is an important anga of devotional service and is the active ingredient of sadhu-sanga, or association with devotees.

Offering Respect to Vaishnavas
In the Chaitanya-charitamrita (Madhya 15.111, purport) Lord Chaitanya defines a Vaishnava and how we should act toward him:
Sri Chaitanya Mahaprabhu then finally advised, `One who is chanting the Hare Krishna mantra is understood to be a Vaishnava; therefore you should offer all respects to him.'

Purport: In his Upadeshamrita, Srila Rupa Gosvami states, krsneti yasya giri tam manasadriyeta dikshasti chet. An advanced devotee should respect a person who has been initiated by a bona fide spiritual master and who is situated on the transcendental platform, chanting the holy name with faith and obeisances and following the instructions of the spiritual master. Srila Bhaktivinoda Thakura comments that serving Vaishnavas is most important for householders. Whether a Vaishnava is properly initiated or not is not a subject for consideration. One may be initiated and yet contaminated by the Mayavada philosophy, but a person who chants the holy name of the Lord offenselessly will not be so contaminated. A properly initiated Vaishnava may be imperfect, but one who chants the holy name of the Lord offenselessly is all-perfect. . . It is the duty of the householder to offer respects to such an unalloyed Vaishnava.
Srila Prabhupada stresses the importance of showing proper respect to Vaishnavas:

People in general must always respectfully honor saintly persons. It is ordered that as soon as one sees a Vaishnava, or even a sannyasi, one should immediately offer respects to such a holy man.* If one forgets to show respect in this way, one must observe a fast for that day. This is a Vedic injunction. One must be extremely careful to refrain from committing offenses at the lotus feet of a devotee, or saintly person. [Srimad Bhagavatam. 9.9.6, purport]

*Sometimes we should refrain from offering a Vaishnava obeisances because doing so might inconvenience him. The Brihan-naradiya Purana forbids us to offer obeisances to a Vaishnava while he is bathing, collecting wood for a sacrifice, picking flowers, carrying water, or honoring prasada. If you are in an impure state--for example, if you are eating, bathing, or wearing shoes, or if your head is covered--you should neither offer nor receive obeisances physically. You are not, however, forbidden to offer respects in your mind; you should then take the next opportunity to offer physical obeisances. These rules apply when offering respects to any superior person, whether a Vaishnava or non-Vaishnava. A further consideration is that there are two times when we should offer obeisances to a superior, namely first when we see the superior person, and againi when he or she sees us.

All Vaishnavas, even ordinary ones, should be shown respect. However, the respect shown may be more or less elaborate according to the advancement of the devotee being received. (See the section ``Pancharatra Pradipa - Reception of Guests," pg. <?>). Thus even to Vaishnavas of the least advanced category you should offer polite words and show outward respect, but you may avoid their association.

Lord Kapila elaborates on this point:
Even if one is a Vaishnava, if he is not of good character his company should be avoided, although he may be offered the respect of a Vaishnava. Anyone who accepts Vishnu as the Supreme Personality of Godhead is accepted as a Vaishnava, but a Vaishnava is expected to develop all the good qualities of the demigods. [Srimad Bhagavatam. 3.29.16]

To other types of Vaishnavas you must at least offer sincere respect in the proper way and show friendship:
When two Vaishnavas see each other they should pay obeisances without reservation, for both should remember that Vishnu resides within each of them. [Tejo-dravina Pañcharatra]

When a learned person stands up or offers obeisances in welcome, he offers respect to the Supersoul, who is sitting within everyone's heart. It is seen, therefore, among Vaishnavas, that even when a disciple offers obeisances to his spiritual master, the spiritual master immediately returns the obeisances because they are mutually offered not to the body but to the Supersoul. [Srimad Bhagavatam. 4.3.22, purport]

For twelve years the Lord will not accept the puja performed by one who sees a devotee of the Lord but fails to approach and respect him properly. [Skanda Purana]

A devotee of the Lord does not demand respect from anyone, but wherever he goes he is honored by everyone throughout the whole world with all respect. [Srimad Bhagavatam. 4.9.47]

Upon seeing a devotee arrive from a distant place, one should approach him, embrace him, introduce him to one's fellow Vai?Šavas, and make him feel comfortable. [Brihan-naradiya Purana]

One who sees a devotee of the Lord in great trouble and anxiety but fails to help him incurs the displeasure of the Lord. [Hari-bhakti-vilasa]

The Skanda Purana warns householders not to slight devotees who come to their homes:
If a person fails to properly welcome a Vaishnava who has come to his house, it becomes like a crematorium, which the forefathers will avoid. There is no greater sinner than one who fails to receive, according to his means, a Vaishnava who has come from a distant place.

Lord Krishna provides the best example of how to receive Vaishnavas:
Krishna is the Supreme Personality of Godhead, worshiped even by Narada, but still, as soon as He saw Narada enter the palace, Krishna got down immediately from Rukmini's bedstead and stood up to honor him. Lord Krishna is the teacher of the whole world, and in order to instruct everyone how to respect a saintly person like Narada Muni, Krishna bowed down, touching his helmet to the ground. Not only did Krishna bow down, but he also touched the feet of Narada and with folded hands requested him to sit on His chair . . . When . . . He washed the feet of the sage Narada and took the water on His head, Narada did not object, knowing well that the Lord did so to teach everyone how to respect saintly persons.* [Krishna, 'The Great Sage Narada Visits the Different Homes of Lord Krishna']

*One may ask, "What if someone wants to touch my feet? How should I respond?" In a letter, Srila Prabhupada answered this often-asked question as follows: "You do not allow anyone to touch your feet--this is very good attitude--but if they want to insist on touching your feet and there is no other way to avoid it, you can simply remember your predecessor Acharyas and Spiritual Masters and accept them and return namaskars with folded hands. That is the Vaishnava etiquette" (letter from Srila Prabhupada, 4 April 1970).

As aspiring Vaishnavas ourselves we try to lend a hand to those of the ordinary category, encouraging and supporting their development; our peers of the transcendental category we share realisations with, encourage and associate with; the more advanced Transcendentalist we associate with, learn from, and accept shelter from, for they have seen the truth Bhagavad Gita 4:34.

This is not meant to be presented in a judgmental way, but certainly we need to learn how to discriminate, so that we can take full advantage of the positive and avoid committing offenses by engaging in negative worldly activities. Needless to say we need to return to that place which is free from the three fold miseries that always afflict us. So this site is there to help in our sojourn years.

However, there are also deviant devotees, the apasampradayas as mentioned in the following LINK: