Lauren M. Fisher
I started with only a small story. Granted that story didn't pan out, but I absolutely loved creating it. I wrote it with my best friend in high school. If you have an idea, write it down. And then research. Make sure you read the genre of your story, and take notes on how the authors develop characters or their particular writing style. The only way you get better is by writing more and more, having someone who can edit and give you criticism, and reading as much as you can.