1) Call the police and find out what you can do.
2.) Talk to the neighbors, try to maybe get a neighborhood watch going?
3.) If you are convinced that they're druggies, do your best to watch out for them, and if you happen to see anything that screams HEY IM DOING SOMETHING ILLEGAL take a photo or call the police on the spot.
4.) Adopt some big doggies, people tend to have their hearts drop to their stomach when they hear a big bark and they're doing something wrong
