There are many things to remember when dealing with a teenager...one is...if you say "NO" have you a good reason for saying it? If you haven't then please don't say it!
TRUST your children...show them trust even when you may feel that they will abuse it....they have to live with it as well as you! When they abuse your trust...deal with it in the best way you see possible.
You have to trust your partner when he/she goes out of your sight so why not trust your kid?. Please don't try to anticipate what your child might do...or you may make difficulties where they may not exist.
Most of all...show your children LOVE...whatever they do and support them through thick or thin......that's life!
Best wishes, Mike.