Take A Step Back
Parenting teens is no easy task. The first thing that you need to do, no matter how angry you are, is to take a small step back and realize what is really happening with your teen. To do this, you need to realize what they are facing. They are facing peer pressure, constant rejection from friends and are usually struggling with their self image. They are under a lot of stress and do not need you to add to it.
No matter what you see when you take your step back; you need to react to it. If you are thinking that you do not need to worry about your child because they will make the right choices, you are welcoming their pain. Instead, you need to pull them aside when they are having trouble and talk to them in a frank yet understanding way. For example, if you suspect that your child is doing drugs, sit down with them, tell them what you think is happening and offer to help them to get them back on track. No accusations, no pressure, just you being a parent.
Realize that all children make mistakes, even teens. The mistakes teens make are just bigger and more life threatening than those that toddlers make. Yet, parenting teens means being a parent to them. Realize what is happening to your child. Realize what you need to do about it. Forgive them for making the mistake and help them to get out of it. You will need to do this type of parenting for as long as you have teens.