Parents need to present a united front. Talk an issue over ahead of time rather than disagree in front of the child. Realize that you are humane. Every parent makes mistakes, and we can only do the best be can. This is not old fashioned advise, it's common sense.
Kids can go to school related activities with adult supervision without too much worry.
Know the adults involved with rides, and those where your kids go to spend the night. Your teenager's friends can have more influence on him than you can imagine. Kids will usually do whatever they can get away with. Young teenagers do not have the maturity to withstand peer pressure. Give your child self confidence.