4. Know your children's friends and their families.

Friends have a strong influence on each other, so help your children and teenagers become friends with kids whose families share your values. Some parents of teens even arrange to meet with the parents of their children's friends to establish common rules and expectations. It is easier to enforce a curfew that all your child's friends share rather than one that makes him or her different - but even if your views don't match those of other parents, hold fast to your convictions. Welcome your children's friends into your home and talk to them openly.