Remembrance of the Supreme Personality of Godhead within one's heart is the goal of devotional service. When devotional service is performed purely and affectionately, there is no question of regulative principles. There are no do's and don't's.
However, one should generally accept the following principles to properly execute devotional service: (1) take shelter of a bona fide spiritual master, (2) receive initiation from the spiritual master, (3) serve the spiritual master, (4) inquire and learn love from the spiritual master, (5) follow in the footsteps of holy persons devoted to the transcendental loving service of the Lord, (6) prepare to give up all kinds of enjoyment and miseries for the satisfaction of Kṛṣṇa, (7) live in a place where Kṛṣṇa had His pastimes, (8) be satisfied by whatever is sent by Kṛṣṇa for the maintenance of the body and hanker for no more, (9) observe fasting on Ekādaśī day (this occurs on the eleventh day after the full moon and the eleventh day after the new moon. On such days no grains, cereals or beans are eaten; simply vegetables and milk are moderately taken, and chanting Hare Kṛṣṇa and reading scriptures are increased.), (10) show respect to devotees, cows and sacred trees like the banyan tree.