How to Write a Step Outline for Your Script
A step outline gives you a bird's eye view of your overall story. Slightly more detailed than a treatment, the step outline should end up about 10 to 12 pages when finished. Creating the step outline helps maintain focus on the main story instead of getting drawn into the details. The step outline process should also help cut down the the number of inevitable rewrites by giving you a chance to spot structural deficiencies in your screenplay's story and characters,
Write each step as an event rather than a specific scene. In other words, each step is made of a set of scenes. This will help keep you out of the story details prematurely.
Keep your steps short and to the point. A step should ideally be only one to two paragraphs. If you have an idea for a characterization or a piece of dialogue, go ahead and include it in the step, but keep it succinct.
Capitalize your characters' names and the props the same as in full screenplay format.
Format the step outline for a short film to include the slug lines or scene headings above each step. In a 10-minute film, this will make drafting the finished script progress much more quickly.