I only ask out of curiosity so that I know what not to do.

Every sin is totally forgiven when one sincerely repents and resolves to improve. True, there are several sins which are said by our sages to be "unforgiveable", but even then, they teach that this statement is just part of the challenge. For when a person improves and repents despite being told that he has no chance, his improvement is inherently that much more sincere and idealistic and not out of ulterior motives (e.g. fear of punishment). It's important to add that sins against our fellow man are not forgiven by God, unless we first ask and receive forgiveness from our neighbor.