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 GaimanI feel like I am involved in an obscure and complex version of poker in a pitch-dark room, with blank cards, for infinite stakes, with a dealer who won't tell me the rules, and who smiles all the time.
Neil Gaiman