Schools I recommend taking acting classes as much as possible. Classes not only help refine your acting technique, they help you discover yourself and grow as a person. It's also fun to be with others who share your passion. If you're already in school, take drama as an option. Open your local yellow pages.
Some theatre companies offer classes too.
Sometimes the only way to find out if they do is to call and ask. If you have some experience in school or independent theatre productions, list your credits on a neatly typed and formatted resume. You may want to include information on where the production was performed, what school or theatre company put the production on, and what part you played. Every actor who's actively looking for acting work must have a resume photo. When you're first starting out, you don't have to spend hundreds of dollars.