One should look unto the Lord; one should not be disturbed by the so-called manifestations of happiness or distress, but he should try to cooperate with the Lord in His outward activities for correcting the fallen souls. By His order only, one should become a spiritual master and cooperate with the Lord. One should not become a spiritual master for one's personal benefit, for some material gain or as an avenue of business or occupation for earning livelihood. Bona fide spiritual masters who look unto the Supreme Lord to cooperate with Him are actually qualitatively one with the Lord, and the forgetful ones are perverted reflections only.
(Srimad Bhagavatam---1:13:48---purport).

One can achieve the nucleus of the devotional service of the Lord by the mercy of the spiritual master and the Personality of Godhead. The spiritual master is the manifested representative of the Lord to help one achieve ultimate success. One who is not authorized by the Lord cannot become a spiritual master. Śrīla Śukadeva Gosvāmī is an authorized spiritual master, and thus he was inspired by the Lord to appear before Mahārāja Parīkṣit and instruct him in the teachings of Śrīmad-Bhāgavatam.
(Srimad Bhagavatam---1:19:36---purport).

Simple theoretical book knowledge is not sufficient for a neophyte devotee. Book knowledge is theoretical, whereas the arcana process is practical. Spiritual knowledge must be developed by a combination of theoretical and practical knowledge, and that is the guaranteed way for attainment of spiritual perfection. The training of devotional service for a neophyte devotee completely depends on the expert spiritual master who knows how to lead his disciple to make gradual progress towards the path back home, back to Godhead. One should not become a pseudo spiritual master as a matter of business to meet one's family expenditures; one must be an expert spiritual master to deliver the disciple from the clutches of impending death.
(Srimad Bhagavatam--2:3:22--purport).

Even if one is fixed in devotional service like Mahārāja Parīkṣit, he must still inquire from the realized spiritual master all about this. In other words, the spiritual master must also be well versed and learned so that he may be able to answer all these inquiries from the devotees. Thus one who is not well versed in the authorized scriptures and not able to answer all such relevant inquiries should not pose as a spiritual master for the matter of material gain. It is illegal to become a spiritual master if one is unable to deliver the disciple.
(Srimad Bhagavatam---2:8:7---purport).

One should not be eager to become a spiritual master cheaply for the sake of profit and fame, but should become a spiritual master only for the service of the Lord. The Lord never tolerates the impertinence of maryādā-vyatikrama. One should never pass over the honor due to an elderly spiritual master in the interests of one's own personal gain and fame. Impertinence on the part of the pseudo spiritual master is very risky to progressive spiritual realization.
(Srimad Bhagavatam---3:4:26---purport).

Gosāñi means gosvāmī. A person who has full control over the senses and mind is called a gosvāmī or gosāñi. One who does not have such control is called a godāsa, or a servant of the senses, and cannot become a spiritual master. A spiritual master who actually has control over the mind and senses is called Gosvāmī. Although the Gosvāmī title has become a hereditary designation for unscrupulous men, actually the title Gosāñi, or Gosvāmī, began from Śrī Rūpa Gosvāmī, who presented himself as an ordinary gṛhastha and minister in government service but became a gosvāmī when he was actually elevated by the instruction of Lord Caitanya Mahāprabhu. Therefore Gosvāmī is not a hereditary title but refers to one's qualifications. When one is highly elevated in spiritual advancement, regardless of wherefrom he comes, he may be called Gosvāmī.
(Sri Caitanya Caritamrta---1:7:13---purport).

The spiritual master must never be carried away by an accumulation of wealth or a large number of followers. A bona fide spiritual master will never become like that. But sometimes, if a spiritual master is not properly authorized and only on his own initiative becomes a spiritual master, he may be carried away by an accumulation of wealth and large numbers of disciples. His is not a very high grade of devotional service. If a person is carried away by such achievements, then his devotional service becomes slackened. One should therefore strictly adhere to the principles of disciplic succession.
(Nectar of Devotion).

A real brāhmaṇa is the natural teacher or spiritual master. Unless one has Vedic knowledge, one cannot become a spiritual master. The perfect knowledge of the Vedas is to know the Lord, the Personality of Godhead, and that is the end of Vedic knowledge, or Vedānta. One who is situated in the impersonal Brahman and has no information of the Supreme Personality of Godhead may become a brāhmaṇa, but he cannot become a spiritual master. It is said in the Padma Purāṇa:
ṣaṭ-karma-nipuṇo vipro
mantra-tantra-viśāradaḥ
avaiṣṇavo gurur na syād
vaiṣṇavaḥ śva-paco guruḥ

An impersonalist can become a qualified brāhmaṇa, but he cannot become a spiritual master unless and until he is promoted to the stage of a Vaiṣṇava, or a devotee of the Personality of Godhead. Lord Caitanya, the great authority of Vedic wisdom in the modern age, stated:
kibā vipra, kibā nyāsī, śūdra kene naya
yei kṛṣṇa-tattva-vettā, sei 'guru' haya

A person may be a brāhmaṇa or a śūdra or a sannyāsī, but if he happens to be well versed in the science of Kṛṣṇa, then he is fit to become a spiritual master. (CC-2:8:128) The qualification, then, of a spiritual master is not to be a qualified brāhmaṇa, but to be well versed in the science of Kṛṣṇa.

One who is conversant with Vedic wisdom is a brāhmaṇa. And only a brāhmaṇa who is a pure Vaiṣṇava and knows all the intricacies of the science of Kṛṣṇa can become a spiritual master.
(Srimad Bhagavatam---3:6:30---purport).