Of all the crap advice I've heard bandied out to freelancers, this has to be the worst: "When you're starting out, you should be prepared to work for free."
Why should you work for free? Arguments range from "getting your name out there" to "building your portfolio." And I don't believe any of it. It might not be easy at first, but that doesn't mean you have to go hungry and play the starving artist. The people you're working for make money, and so should you.
Try building up paying work by doing something on the side. This'll give you time and money to pursue what you really want to do and, as happened to me, may lead you to discover you want to do something quite different.
If you're going to work for nothing, make it for your own website/blog, a friend, or for a charity or good cause. Otherwise, insist on getting paid. If you don't think you're worth it, why would anybody else?
UPDATE: Seems it's not just me thinking about this. Co.Design has this piece Freelancers: How Not To Get Screwed By Clients