Dīkṣā or initiation actually means to take a vow to chant the holy names of the Lord. This is the main rule; because by dint of His holy name alone can one attain the Supreme Lord. There is no other process prescribed in the scriptures. By chanting His holy names alone can one obtain Kṛṣṇa. Therefore this initiation ceremony is known as Harināma-initiation.

Harināma-initiation means, a devotee takes a vow to chant the holy names of the Supreme Lord. Devotees to be initiated are alarmed that when they render devotional service unto the Supreme Lord especially by chanting His holy names, all their sins in the past are destroyed. But due to being unaware of proper knowledge about the offenses to be avoided while chanting, they commit offenses. One should know what is the nature of these offenses and avoid them. The word offense which in Sanskrit is known as ‘aparādha’ can be split into two parts viz. ‘apa’ and ‘rādha’. ‘apa’ means negation of ‘to please or worship someone’ and ‘rādha’ means to ‘to please or worship’. Therefore the word ‘aparādha’ means that which creates hindrance in getting benefitted. For example, electric current flows through a metal wire. If that metal wire is insulated with plastic, then that plastic insulation is said to be creating ‘aparādha’ of the electric current flowing through the metal wire. If someone touches such plastic insulated metal wire, he won’t feel any electric shock. Scriptures instruct us that there is a possibility to commit ten offenses while chanting the holy names of the Lord. One should carefully try to avoid them. If one chants holy names offenselesely, he can surely obtain Kṛṣṇa-Prema (love of Godhead). 

bahu janma kare yadi śravaṇa, kīrtana

tabu ta’ nā pāya kṛṣṇa-pade prema-dhana

(Śrī Caitanya Caritāmṛta, Ādi 8.16)

If one is infested with the ten offenses in the chanting of the Hare Kṛṣṇa mahā-mantra, despite his endeavor to chant the holy name for many births, he will not get the love of Godhead that is the ultimate goal of this chanting.