This process is summarized by Rūpa Gosvāmī in Bhakti-rasāmṛta-sindhu (1.4.15-16): The first requirement is faith; it is due to faith that one associates with pure devotees, and, by such association, develops devotional service. As devotional service develops, one's misgivings diminish. Then one is situated in firm conviction, and from that conviction he develops a taste for devotional service and advances to the stage of attachment, whereby he follows the regulative principles of devotional service. After that point, after one makes further progress, he attains the state called bhāva, which is permanent. When such love of God increases, it reaches the highest stage of love of Godhead."
In Sanskrit this highest stage is called premā, premā can be defined as love of God without any expectation of exchange or return. Actually the words premā and love are not synonymous, yet one can say that premā is the highest stage of love. One who has attained premā is the most perfect human being. Śrīmad-Bhāgavatam also confirms this statement (SB 3.25.25): Only by the association of pure devotees can one develop a taste for Kṛṣṇa consciousness, and when he tries to apply Kṛṣṇa consciousness in his life, he can achieve everything up to the stage of bhāva and prema.