Having some idea of the kinds of films you intend to make will help you narrow the field when applying to film schools. The school you choose should have a program that meets your needs and interests. Ideally, it will also have a reputable history, a location that allows you to take advantage of film internships and jobs, and its teachers will have worked directly in some aspect of the film industry.
A key element to your film school application is a five- to ten-minute sample movie. It isn't necessary to own your own equipment or have fancy special effects, but your sample should give the school a good feel for what you already know. It also makes sense to produce something in the same vein as the types of films you'd like to study and ultimately create as a professional, and make it your best.
A good way to become comfortable with stories is to take as many writing courses as you can. Creative writing courses give you practice fleshing out your ideas. A mantra of prose writing is "show, don't tell," and film-making becomes the ultimate in bearing that out. Also include in your application any screenplay or animation storyboard you have.
Any opportunity you have had to take acting, directing, theater, or film courses should be included in your application. Consider your experiences and how they might apply to your film career. For instance, directing a community theater play would give you hands-on knowledge of working with actors. Being an actor in a production gives you experience with interpreting a story. If you plan to include film school in your future, take the opportunities that come along to prepare you for it.