I've been writing articles in the Great Lakes Trail Riders for about 10 years now and have not been paid one cent. Then again I haven't asked for any money either. I also didn't start writing with the idea of making a living at it either, I was just passing on some information I knew. Now I not only send my articles to the GLTR editor I send them to a ORV magazine in Montana, NOHVCC, and a Hare Scrambles web site in Arkansas.
All of them still for free, Why? Because I'm crazy mostly the other is a love for this sport that can't be explained. Also I hate bench racing and hearing stories of how somebody felt helpless when their buddy got hurt, when I had the information to help out, and now it's too late.
You've gotten some good advice in here, I would echo the statement of starting small and work your way up, send stuff to the GLTR, Tim is always looking for stuff to print. Send stuff to the D-14 paper, looking at race results gets boring every month. This way you build up a portfolio, so when you want to hit the big guy's you have something to show them. Also... Write what you know about and what your passionate about, people know when your writing a bunch of BS and will skim right past it.
RJ