Here are some topics that should be discussed with your child:
-Sexually transmitted diseases (STDs): teens curious, mostly curious about sex. What many don't realize the risks associated with sex? Many foci solely on use, to get pregnant, have little knowledge about sexually transmitted diseases and how to refer them. Although some of these may seem simple to you too, your kids probably never heard everything important and just looked up what they feel comfortable with science.
-Alcohol and drug abuse: it's serious stuff, especially when used by an experienced user (drugs by anyone). You need to talk to your teen about this and tell them the risks, not just as bad for them, but what can happen to them (like being taken advantage of).
-Tattoo and body piercing risks: getting a tattoo often rites of passage for many teenagers. Even if it is set that you only have certain reservations, and maybe I should go with them to find clean and well spoken of tattoo or piercing parlor who agrees to go with them. This way you can ensure their safety, and do something with your child.
-Advice: let them know that depression sometimes it happens to everybody, and if they don't feel comfortable talking with you, maybe going to a counselor would be good. Get rid of the stereotype that there is something wrong with someone who wants someone objective to talk; it's okay. This way you can also get a feel for what your child needs if it is depressing or only unbalanced hormonal that can be fixed with medication.