How much to charge?

The question of how much to charge for your work plagues every new freelancer. Most, like me, tend to underprice themselves, afraid if they charge too much no one will buy. Further, they don't believe they're worth as much as they could get. It's really hard to break out of that! What I'm doing is I set my hourly rate at $25 per hour. I try to figure out how much time I'll spend researching and writing the piece and guess at a price from there. It's really pretty unscientific. I almost always underestimate how much time something will take...and then, I forget about the whole rewrite thing. While some pieces are just fine the first time I write them, others require rewrites. These are usually minor things; often the editor thought of something I should add after they read the first draft, or they give me some information I didn't have before. It's rarely earth shattering, but it is practically inevitable and I need to remember to build it into my time. I also need to consider the time I sit and stare at my computer, creating the piece in my head before I actually write. It is a process I will probably need to continually readjust.