The first stage for any project is PLANNING.

For me step one would be to create a Script or Storyboard. Figure out who the actors are, what roles they play, what props (table, trees, car, house) will be in each scene. You will have to essentially think like a director. Find out if the short will be with voice dialog or with subtitles.
With the completed script, create scenes and plan out what is the best position of the camera to capture the idea in the scene.
Its all about planning.