when i was 17 years old, I didn't know the first thing about making music digitally. 4 years later, I see some major results and get some remixes posted here. A lot can happen in a small amount of time--and you have a lot of time!
Anyway, the answers to this question I hear a lot include "make all the contacts you can", "take whatever job you can", etc. But if you're looking to hone your skills, you can take either the formal composition route or the music producer route.
This website right here is an excellent place to learn about the digital production of music--it's where I learned everything I know. Post works-in-progress for feedback, join #ocremix and #ocrwip for help in realtime in irc (irc.enterthegame.com), read the judges decisions to get an idea of what a site like this looks for production-wise... all of these things helped me tremendously. If you're thinking about colleges, there are schools out there with good production programs... I know zircon's had a lot of success over at Drexel in Philly.
As for composition solely, another site that could be of help is http://www.youngcomposers.com . Whereas we're all about mp3s and phat beats, they're more about midis, scores, and other classically-inclined (but not strictly classical) errata. As for schools, going to school for composition isn't a bad idea--just make sure you do indeed like classical/orchestral music or else you might get miserable But I have many composer friends at my school who are going on to get film, and even video game composing gigs.
But I'm not the best person to ask. There are a few professional composers about the site. Hopefully Wingless will find this thread soon!