If by the tongue you chant Hare Krishna mantra and by the tongue you taste prasadam, you will be perfect, simply by executing these two things.
Always remember Krishna who is your dear most friend and always serve Him just to please Him and He will give you all intelligence how to be a first class devotee.
If one renders even a small amount of sincere devotional service, Krishna becomes obliged to elevate such person and what to speak of one whose entire life and soul has been dedicated to Krishna’s service.
Devotional service is dependent on the mercy of Krishna and His devotees. Unless we surrender to the lotus feet of a pure devotee, it is not possible to come to the platform of pure devotional service. By his own efforts a bee cannot taste the honey within a bottle. The bottle must be opened by a superior. If the bee simply licks the outside of the bottle, thinking “Now I am tasting honey,” then he is in illusion. Similarly, no one can enter into devotional service unless the door is opened by a devotee.