Conviction

What is sin to one person may not be to another. I have realized this over and over again as I have saturated myself in a Christian environment that I normally don't get when I'm at home with my family, I tend to gravitate toward the people in my college ministry group and spend a ridiculous amount of time with them. What I choose to abstain from, what they choose to abstain from...what isn't clearly stated in scripture (ie adultery, stealing, lying) is based on conviction. Sure, sometimes we mess up but that's where forgiveness comes in...but where do we draw the line in what is sin and what isn't? The answer is the Holy Spirit but other than that, I honestly don't know for sure but I have a general idea. I do realize everyone's different. For me personally, I think that if you're not sure about something, don't do it. Sometimes I like to question things though. Many others do too and if you're one of those people and still don't know, consider these questions:
1. Why are you doing it?
2. How does it benefit you?
3. How is it affecting you spiritually?
4. Can it be considered a stumbling block for people around you?
5. Is it something you did pre-salvation? If it is, how did it affect you then?
6. Would I still do this if God was sitting across from me and I could physically see Him?

What do you guys think? Do you have anything to add? Any thoughts?