I have a great story idea, and I can't wait to finish the rewrite. It's sort of a romance, something of a thriller, definitely a psychological drama. Because the rewrite makes it an evolving story, I'm not sure which genre it fits into. While most novels contain elements of multiple genres, one should dominate, assuring buyers they're getting the kind of story they want to read. Readers have expectations, which is why genre is essential if your goal is to sell books and build a fan base. A reader of horror may be upset if the ebook she just downloaded is a yarn about two young sisters that takes place during a storm—and one of them is horrified of lightning. Sci-fi aficionados will not likely be pleased if the science-fiction-type cover of their latest purchase wraps around a major love story that overshadows the anticipated futuristic drama. Consider the following scenario: A sweet old lady purchases an author-advertised "young adult" mystery for a pre...