One thing I will say as a fellow young technician: Don't work for free. Believe it or not, your time is worth money, and believe me, thier are Production Mangers that will take advantage of you. Don't take more than 3 "trial hours", "training hours", ext.
Ask various Production companies around town. At the very least you can push
road cases, hang lights, run
power. Say thank you and learn quick: They'll
call you again.
As to classes, and Tech
Theatre, A/V production, Physics is a
bit helpful. Understanding Networks is helpful for intelligent stuff.
ETC has some good online resources. J Michelle Gillette's
Design and Production for Theatre is an awesome resource for various theatrical things.
Summer
Stock Theatres are another great way to learn and get into the industry. Some pay, some don't. HS & college ones are the best for you age, but they're kind of rare.
I've found that thier are 3 major bodies of knowledge and skills that are great to know in
theatre and production. First is
power: generators, Distros, Saxopex, How to draft and spec
power plots ext. Second is
DMX: running cable, addressing, patch listing, and troubleshooting. Third is running consoles. If you can learn a solid knowledge
base in one of these area, you become an extremely valuable employee. Not to say that you need to become a master of one of these, but if you're looking to learn about the industry. Those are great places to focuses to start in.
Power is going to be the most valuable for movies and TV,
DMX or consoles for
Theatre and Event Production.
Solid knowledge
in one of these and a good resume will also go a long ways into getting you into good colleges for
Theatre and Production.
Good luck my friend.