Writing a screenplay is a very complex process and will end up as a 100+ page document. So before you write it, it is very helpful to create a blueprint of what you are going to write, starting first with a treatment, and then writing the outline. You should first create a treatment of your story and work that out. (See related article.) Once you have the treatment worked out, then you could write the outline.
An outline should contain heading for every scene in your script. It doesn't have to have all the establishing shots yet, but it should outline and note every major scene that will happen. You would format the scene headings properly and essentially be creating the skeleton of your script, but doesn't yet include all the details.
The outline will contain the actual scene headings and it will also have lines of description that will be in the final script.
It can also have some dialogue in it, but only in places where it is easier to write the dialogue of a character than to describe what they do and say.
The outline will lay out where things will go, more for structure purpose. You also can put in "placeholders." So, for example, you might put in a scene heading and then beneath it, write: "This is where Veronica will listen to the phone messages and discover that Blake has been seeing someone else." That would be considered a placeholder for that scene that you will come back and flesh out later.
If you likened the outline to building a house, you could think of the outline as being the architect's blueprint and the contractor's foundation with the support beams. The treatment is more like a full-color sketch of the interior of the house, while the outline is the foundation and support beams and walls and so on.
With the outline, you are getting the pieces in place that are important to the story, but it doesn't have the feel of the "house" or the screenplay yet.
An outline is more of a work in progress developing into the screenplay just like a house being built, while the treatment is a story that is whole and complete in and of itself. You could think of the treatment as a miniature or scale model of the whole thing.
An outline can be anywhere from 7 to 30 pages. Single-spaced within the paragraphs with a double space between paragraphs. Use a 12-point font that is easy to read (Arial, Courier, Times New Roman).
Melody Jackson, Ph.D., is the founder of Smart Girls Productions, a Hollywood Marketing Company supporting Screenwriters in moving their careers forward. If you are ready to jump-start your career, increase your confidence, and have more fun pursuing Hollywood success, get "Plugged In" at http://www.QueryLetterMailings.com Also get your FREE REPORT on "The Top 20 Literary Agents In Hollywood," along with Hot Tips on Marketing Yourself To Hollywood. Melody has critiqued thousands of screenplays in depth and was rated a Top 5 Script Consultant in the country by Creative Screenwriting Magazine. Go to http://www.ScriptCritiques.com for more information on marketing to Hollywood.