The more involved you are in your children's lives, the more valued they'll feel, and the more likely they'll be to respond to you. Don't be afraid to ask where your kids are going, who they'll be with and what they'll be doing. Try to be there after school when your child gets home. If your child will be with friends, ideally they have adult supervision - not just an older sibling. Eat together as often as you can.
Meals are a great opportunity to talk about the day's events, to unwind, reinforce, bond.
Studies show that kids whose families eat together at least 5 times a week are less likely to be involved with drugs or alcohol. The more you communicate, the more at ease your child will feel about discussing drugs and other sensitive issues with you. Be absolutely clear with your kids that you don't want them using drugs. Don't leave room for interpretation. And talk often about the dangers and results of drug and alcohol abuse.