Many books on writing tell you to write about what you know. I say bull. Don't be afraid to write about something you know littel about. If it motivates you to write a story, then do it. Your job, first and foremost, is to write about interesting characters dealing with interesting problems. The grunt work of research and rewriting can come later. The important thing is to ride the wave of inspiration for as long as it lasts; get the story out of your head and onto the page.
In his book, On Writing. Stephen King says much the same thing: "When you step away from the 'write what you know' rule, research becomes inevitable, and it can add a lot to your story. Just don't end up with the tail wagging the dog; remember that your are writing a novel, not a research paper. The story always comes first.