In my bible beside Proverbs 22:6 there is a note taken from a sermon that says" this is a proverb, not a promise" I will do my best to follow it either way. With 2 girls (oldest is only 5) I do a lot of praying and try to use every chance I get to take care of business now, so it won't be so hard later.
There is a lot of great advice in this thread. I certainly believe that threatening them with their life can't hurt. Neither can showing them the "black gun" that is in the collection

I know every road in this county and don't really need much sleep anymore. I WILL follow them, show up at their friend's house, hide on the back row of the movies, or whatever it takes to do all that I need to do. That being said, You can only do your best. We have all seen great parents and rotten kids. No one can really explain it, but sometimes it just happens. As your child EARNS TRUST, you will know how to handle it. Squash them when they break that trust. When it is all said and down and I have to give an account on how I handled my most prize possesions, i don't want to be squirming.