Lord Caitanya said that one who is master in the science of Kṛṣṇa consciousness, regardless of his social position, is the real spiritual master.
kibā vipra, kibā nyāsī, śūdra kene naya
yei kṛṣṇa-tattva-vettā, sei 'guru' haya
"It does not matter whether a person is a vipra (learned scholar in Vedic wisdom) or is born in a lower family, or is in the renounced order of life-if he is master in the science of Kṛṣṇa, he is the perfect and bona fide spiritual master." (Caitanya-caritāmṛta, Madhya 8.128) So without being a master in the science of Kṛṣṇa consciousness, no one is a bona fide spiritual master.

(Bhagavad-Gita------2:8-------purport).

Persons who are householders without Kṛṣṇa consciousness are constantly tarrying in material life, in spite of all kinds of inconveniences. In family life, or any life, one cannot be perfectly happy without being Kṛṣṇa conscious. Śrīla Narottama dāsa Ṭhākura prays that he will have the association of a person—either a householder or a man in the renounced order of life—who is engaged in the transcendental loving service of the Lord and is always crying the holy name of Lord Caitanya. For the materialistic person, worldly affairs become too aggressive, whereas to a person who is in Kṛṣṇa consciousness, everything appears to be happily situated.

(Krsna Book).

One who has the sex desire still with him should not at all try to accept the renounced order of life. For one who has not attained to this stage, there is no question of a renounced order of life. So by the gradual process of devotional service under the guidance of a proper spiritual master, and following the principles of the Bhāgavatam, one must be able at least to control the gross sex desire before one accepts the renounced order of life factually.

(Srimad Bhagavatam-------2:2:12-------purport).

The realization that one is the infinitesimal part and parcel of the Supreme Spirit makes him unattached to material, conditional life. That is the beginning of devotional service. Unless one is liberated from material contamination, one cannot engage himself in the devotional service of the Lord. In this verse, therefore, it is stated, jñāna-vairāgya-yuktena: when one is in full knowledge of one's constitutional position and is in the renounced order of life, detached from material attraction, then, by pure devotional service, bhakti-yuktena, he can engage himself as a loving servant of the Lord. Paripaśyati means that he can see everything in its right perspective. Then the influence of material nature becomes almost nil.

(Srimad Bhagavatam-------3:25:18-------purport).

One should not remain a householder throughout his whole life; he must always remember that there are four divisions of life—brahmacarya, gṛhastha, vānaprastha and sannyāsa. So after gṛhastha, householder life, one should retire. If one lives for a hundred years, he should spend twenty—five years in student life, twenty-five in householder life, twenty-five in retired life and twenty-five in the renounced order of life. These are the regulations of the Vedic religious discipline.

(Bhagavad-Gita------16:1-3-------purport).

Females are not meant for the renounced order of life; they should be faithful to their good husbands, for if a husband is competent for liberation, his wife will also achieve liberation with him. As stated in the śāstra, the results of a husband's pious activities are shared by his wife. Therefore a woman's duty is to be very chaste and faithful to her husband. Then without separate endeavor she will share in all the profit the husband earns.

(Srimad Bhagavatam-------6:6:1-------purport).

One should strictly follow the regulative principles, namely no illicit sex, no meat-eating, no intoxication and no gambling, and in this way one should make progress in spiritual life. If an unfit person sentimentally accepts vairāgya or takes sannyāsa but at the same time remains attached to women, he is in a very dangerous position. His renunciation is called markaṭa-vairāgya, or renunciation like that of a monkey. The monkey lives in the forest, eats fruit and does not even cover itself with a cloth. In this way it resembles a saint, but the monkey always thinks of female monkeys and sometimes keeps dozens of them for sexual intercourse. This is called markaṭa-vairāgya. Therefore one who is unfit should not accept the renounced order of life. One who accepts the order of sannyāsa but again becomes agitated by sensual disturbances and talks privately with women is called dharma-dhvajī or dharma-kalaṅka, which means that he brings condemnation upon the religious order. Therefore one should be extremely careful in this connection.

(Sri Caitanya Caritamrta-------3:2:120-------purport).

The Lord has described various kinds of knowledge and processes of religion—knowledge of the Supreme Brahman, knowledge of the Supersoul, knowledge of the different types of orders and statuses of social life, knowledge of the renounced order of life, knowledge of nonattachment, sense and mind control, meditation, etc. He has described in so many ways different types of religion. Now, in summarizing Bhagavad-gītā, the Lord says that Arjuna should give up all the processes that have been explained to him; he should simply surrender to Kṛṣṇa. That surrender will save him from all kinds of sinful reactions, for the Lord personally promises to protect him.

(Bhagavad-Gita------18:66-------purport).

Renunciation means not doing anything but serving the Supreme Personality of Godhead, Śrī Kṛṣṇa. When one acts on this platform, trying to please the Supreme Personality of Godhead, one is both a sannyāsī and a yogī. This is confirmed in the Bhagavad-gītā (6.1):
śrī-bhagavān uvāca
anāśritaḥ karma-phalaṁ kāryaṁ karma karoti yaḥ
sa sannyāsī ca yogī ca na niragnir na cākriyaḥ
"The Supreme Personality of Godhead said, "One who is unattached to the fruits of his work and who works as he is obligated is in the renounced order of life, and he is the true mystic, not he who lights no fire and performs no work.""

(Sri Caitanya Caritamrta-------2:10:108-------purport).