Get educated. Know the facts. Once you do, you will realize that it is not worth endangering your career, your health, your relationships, and your future.
Avoid peer pressure. Think ahead about how to say “NO.”
Avoid situations where people will be drinking and using drugs. Get involved in non-drinking activities.
Confront your problem, if you have one.
Get help for the underlying problems of family, relationships, anxiety or depression. Educate others.