For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Love God with all you've got and love your neighbor as yourself. All the law is summed up in these two commandments. (My paraphrase)
If you want to know if what you did, are doing or are about to do is a sin, ask yourself this, "Did/will this honor God? Did/will this show love toward my fellow man (image bearer of God)?"
All sin stems from violating these two commandments, so there's your starting point for a list. What you'll soon find is that apart from Christ's work on the cross and the Holy Spirit living in you, you won't even come close to following those two "simple" things. As Christians we reorient our lives so that everything we do honors God. We do this not to earn salvation, but because we have been saved. Not that we have to, but we get to honor God.
Exodus Ch 20:3-17
Proverbs Ch 6:16-19
1 Cor Ch 6:9-10
Gal Ch 5:19-21
These are some biblical lists of sins and a work in progress for me.