Prevention of carpal tunnel syndrome

I find that after only a fair amount of typing on my computer keyboard, I have achy wrists ? it's really getting quite uncomfortable. I am thirty-eight years old, a full-time graduate student, and a full-time professional writer (prose as well as scripts), so I need to do a lot of typing! I am worried about carpal tunnel syndrome (although I don't think that's what I have, at least not yet ? the symptoms are mostly aching in both wrists, on the top). What do you suggest? I can't afford to lose my typing ability (I have a friend who is forty-two, a professional writer, and panicked because she has terrible burning and pain in her arm which has been diagnosed as "over-use syndrome" from typing ? I can't let this happen to me!)