One of the best things to do would be build your own computer, or fool around with an older one that you don't have to worry about breaking.
Experience is a really big thing, but in the corporate environment, so are certifications. MCSE, A+, CCNA are different types of certs you can and should get if you want to get into the field. You can just take the test on your own after reading some books on the subject or take a class. I find a lot of people spend money on the books but don't have the self-motivation to read them and study. Classes on the other hand help with that self-motivation.
Besides that though, you want to get as much computer experience under your belt as possible. Even if it means working for minimum wage at a computer repair shop, its better than nothing (plus what you'll learn from other techs will be priceless).
Also, if you want to be successful you need to get comfortable talking to other people and socializing. Even some of the best techs are not good at dealing with people, which is a priceless quality. Get comfortable talking to others (take some speech classes, project oriented classes). Be willing to get outside of your comfort zone.
Thats some quick advice I have, hopefully it helps!
Shane