S.B.
My oldest daughters, now 21 and 20, could start dating at 16. The boy had to pick them up at the house, I had to meet him, and they had a 10:00 date curfew. At 17 I increased it to 11:00 and at 18 it was Midnight. The only exception was if they were going to a late show and it didn't get over until after curfew or if they were being chaperoned by another adult. I DID check to see if they were where they said they were going to be (movie, dinner, etc). Sometimes they knew I was checking up, other times not. My girls also started on birth control by the time they were 16 and I gave them lessons on how to use a condom as well as made sure they both carried them with them. It wasn't giving them permission to have sex (they were going to decide that no matter what I did), just making sure they were safe. My next daughter in line is going to be 13 in a few weeks and the rules will be the same for her. I don't know that my way is the "right" way but it worked for our family - nobody is pregnant, no one has come home in a cop car, and no one is addicted to any substances. I knock on wood as I say this, of course.
I think the most important thing is that whatever rules you decide, you stick to them as well as the consequences that come along with breaking the rules (girls LOVE to test their parents).
Good luck!