may I recommend outlining your story, and brainstorming it, meaning just throw down what ever ideas you have about the story on paper, then sort them out.
when I started thinking up stories i have and have always been reluctant to write them done. Worse, some times I'll start on one, but insist on starting it from the very beginning, details and all. I even remember one time i ended up stoping because I got hung up on describing the faces and clothing of the characters, rather than focusing on the overall story.
Also setting deadlines for yourself is a good way to keep writing and preventing yourself from putting it off. Also, just focus on the story, don't worry about descriptions or writing style till later when the story is complete, or worry about how you are writing is at the moment (whether in outlining, brain storming, or writing chapters), just focus on the story.