CC Madhya 22.115

guru-pādāśraya, dīkṣā, gurura sevana
sad-dharma-śikṣā-pṛcchā, sādhu-mārgānugamana
Synonyms: 
guru-pāda-āśraya — shelter at the feet of a bona fide spiritual master; dīkṣā — initiation by the spiritual master; gurura sevana — service to the spiritual master; sat-dharma-śikṣā — instruction in the transcendental process of devotional service; pṛcchā — and inquiry; sādhu-mārga — the path of transcendental devotional service; anugamana — following strictly.
Translation: 
“On the path of regulative devotional service, one must observe the following items: (1) One must accept a bona fide spiritual master. (2) One must accept initiation from him. (3) One must serve him. (4) One must receive instructions from the spiritual master and make inquiries in order to learn devotional service. (5) One must follow in the footsteps of the previous ācāryas and follow the directions given by the spiritual master.