I think the one thing you must do to become a folk musician is listen to the music. You could go to concerts or listen on the radio or to albums, but folk music just doesn't happen in a vacume.

I got my start one long cold winter that I spent listening to practically every album they had in my local library. I took me a while to find the folk section, but when I did I realized I'd been wasting my time with the rest of it. I was content with recordings for a few years. Then I started singing (badly). Then I started hanging out with some people who were in to folk and filk (SCAers). Then one day I bought a recorder and some song and lesson books, and I was hooked. Now I play a verity of wind instruments, and I'd sooner quit my job than quit playing. (that's not saying much) But my point is that I've been listening to every thing from Doc Watson to songs written in honor of the latest SCA prince, and I try to be part of a folk music community through the mud cat, and through my friends, and by listening to what people are singing.