Srila Prabhupada's Handwritten Note - 1966

Ten kinds of offenses should be avoided while chanting the Mahamantra:

Hare Krishna Hare Krishna Krishna Krishna Hare Hare.
Hare Rama Hare Rama Rama Rama Hare Hare.

List Of Offenses

Blaspheming a Lord’s devotee.
Considering the Lord and the demigods on the same level or to understand that there are many gods.
Neglect the orders of spiritual Master.
Minimizing the authority of scriptures or Vedas.
Interpreting the Holy Name of God.
Commit sin on the strength of chanting.
Instructing glories of Lord's Name to the unfaithful.
Comparing the Holy Name with material piety.
To Become inattentive while chanting the holy name.
Attachment to material things inspite of chanting the Holy Name.

Try To Avoid All The Above Offenses.