The biggest pitfall to avoid is not writing. Not writing is really, really easy to do, especially if you're a young writer. The hope that elves will come in the night and finish it for you, is a very common one to have. That is my main recommendation - you have to write, and you have to finish what you write and beyond that, it's all detail.
Neil GaimanHe stared up at the stars, and it seemed to him then that they were dancers, stately and graceful, performing a dance almost infinite in its complexity. He imagined he could see the very faces of the stars; pale, they were, and smiling gently, as if they had spent so much time above the world, watching the scrambling and the joy and the pain of the people below them, that they could not help being amused every time another little human believed itself the center of its world, as each of us does.
Neil Gaiman