There's an article in the New York Times that's worth checking out about the screenwriters for You Kill Me: Two Screenwriters with No Complaints. You'll have to go through the free registration process to view it, unfortunately.
I love the title. If you've spent any time in L.A. (or the quieter cafes of San Francisco), you probably did not realize that there were any screenwriters without complaints, let alone two. I point to the article because so often we forget just how long a career path the average screenwriter has before finding success, and just how much work it takes to really professionalize. I've read plenty of one-off scripts that clients swear just need a touch up before they're ready for Spielberg, Costner, Peter Jackson, et al. These people missed the article in Vanity Fair about the eco-friendly furnace in Peter Jackson's studio fueled by 100% biodegradable spec scripts. This is a tough business. It's a tough craft to learn. You have to stick with it and enjoy it if you have any hope for survival.