Be original! If you’re going to rehash an over-used plot vehicle, give it a new twist. If your story is too predictable, you’ll lose readers. If you must use a theme that’s not original, such as zombies, vampires, space battles, or swords and sorcery, make sure your characters are real and interesting enough to carry the story. You see this in romance novels all the time. There’s nothing new about falling in love, but engaging characters who pull you into their emotions make it work.