In this 12th chapter of the Bhagavad-gita As It Is entitled Devotional Service, the path of liberation is explained…
For one who worships Me, giving up all his activities unto Me and being devoted to Me without deviation, engaged in devotional service and always meditating upon Me, who has fixed his mind upon Me, O son of Pṛthā, for him I am the swift deliverer from the ocean of birth and death.
Also a nice description of the qualities of a devotee are given…
One who is not envious but who is a kind friend to all living entities, who does not think himself a proprietor, who is free from false ego and equal both in happiness and distress, who is always satisfied and engaged in devotional service with determination and whose mind and intelligence are in agreement with Me—he is very dear to Me.
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The Hare Krishna Movement 