The first thing you need is, of course, an idea. Try to stick with something simple for your first one–any action that can be split up into smaller parts works well.
You may wish to make an inanimate object appear as though it is alive; for example, a sock inching its way across the floor or a piece of paper that crumples itself up. While brainstorming, keep in mind that you can expect to shoot around 10 photos for every second of film.