I started getting involved in startups when I was around 16, there's a lot I'd do differently and a lot I would do the same if I could go back. Here are some thoughts:
1) Build a network: I'd say that the valuable thing I have done is build a network. Attend industry conferences and events in your area, and become engrained in the startup community. Your age is an advantage, it gets you noticed, and means almost anyone will take a meeting with you. Put yourself in lots of situations that scare you, you'll look back and wonder what the big deal was. The best opportunities come when you're you're at the right place at the right time.
2) Learn to program: I'm 'non-technical', having just finished a degree in business marketing. Only recently have I really started making an effort to learn to program (mostly ruby), but I wish I had done it much earlier. Its important even if you never want to be a developer that you have a strong understanding of how things work and what's possible. Its also frustrating not to have the skills to have an idea and create a prototype, without spending your life savings or bringing on a partner.
3) Seize Opportunities: Early on I wasn't too particular about what opportunities I helped out with, if it got me excited, I was in. This mentality let me try a lot of different things and helped me learn better time management. You'll learn what you like and what you don't like. Don't be afraid to get in over your head.
Best of luck!