this excellent post about writing short stories. I really think it offers solid, real world advice for fantasy, science fiction, and speculative fiction writers. My favorite bit, as it can never be said too much:
"3. Get your best ammunition on the first page. Put whatever makes this science fiction or fantasy up front. Also, don't start with an extended scene that only functions as an info dump. If you think you need a prologue, try breaking the information up instead and salting it throughout the story. Prologues can slow down a reader's immersion in the story."