C.C.
I wish I could say that I understand parenting a teen, but I am just starting out! I do, however, have a little experience in that I am a high school teacher & have coached high school sports for the last 6 years, not to mention that I still haven't had my 10 year high school reunion (so I'm a little young too)...
I liked the idea of approaching the issue from a positive angle to maintain a good relationship, I have tried in my classroom both positive and negative incentives for good behavior...it depends on the kid, and you have to be creative. Do they have a job yet? Maybe you might consider a "real-world" simulation (I believe The Cosby Show did an episode like that with Theo)...they have to pay for privileges with good behavior & good grades (or even a source of income if they work or get an allowance). Decide what each luxury would cost (cell phone, computer, car). If they break curfew, they are late. If they were at a job, their pay would be docked and eventually they would be fired (i.e. NO income). They earn this "income" by completing chores, doing other chores outside their responsibility, good grades, etc. I helped my dad try something like this for my brother who was the same way 2-3 years ago. I was his landlord and his boss & he learned real fast how difficult the real world was. I remember catching him fudge his timecard - he got docked his pay & couldn't pay for many utilities or groceries that week. He never considered doing that again. He actually graduated high school, went to trade school, and is living like a responsible adult (well, as responsible as a 19-year-old boy can be) who is providing for himself, and even managing his money well enough to save a good chunk for future issues!
I know I am not an authority, by any means & I know being a parent is MUCH more different than being a teacher...but I hope I was able to offer a little insight!