BG Chap 11 - Kṛṣṇa's instructions how to render pure bhakti

(a) Bhakti must be performed purely (mad-bhaktaḥ). The devotee should engage in the nine processes of devotional service. The only goal must be Kṛṣṇa’s service, with no desire for attainments in this world.
(b) Bhakti must be free from karma and jñāna (saṅga-varjitaḥ). A devotee should not associate with persons who are against Kṛṣṇa, and he should not become attracted to anything but pure devotion. A devotee, at the same time, should not be envious of those who are inimical, because the karma of such a person has awarded him that mentality. Devotees should remain disentangled from such a person’s karma.
(c) The devotee must be friendly to all (nirvairaḥ). He should be devoid of enmity even to those who oppose the Lord, since he considers that the suffering they cause is brought about by himself alone thru his previous karmas. He must compassionately desire to give Kṛṣṇa consciousness to others.
(d) The work of bhaktas must be for Kṛṣṇa (mat-karma-kṛt). A devotee should use his energy fully in Kṛṣṇa’s service while remaining detached from the fruits of his work. He should engage in such services as building and cleaning the Lord’s temple, or cleaning the gardens containing the flowers and tulasī.
(e) Kṛṣṇa must be the goal of life (mat-paramaḥ). The devotee should remain unattracted to both heavenly and impersonal destinations, and not know anything except Kṛṣṇa as his goal.