Write the idea for your story in as much detail as possible. This is for your eyes only, so allow yourself to ramble freely on the page about the characters and the plot.
Write one sentence describing your hook, which is the line that explains the most attention-grabbing part of your story. Imagine what the tagline would be on a movie poster for your screenplay, and that is usually the hook. Find your hook by asking a "what if?" question about your story. For example, The Terminator is based on the question, "What if a cyborg was sent here from the future to kill the only boy that could save the world from a terrible fate?"
Identify the conflict in your story. The deepest and most successful movies have both external and internal conflict, which is evident in the screenplay. For example, Luke in Star Wars exhibits the obvious conflict of needing to save the galaxy from a dark force. He also has to deal with the internal conflict that comes with learning the truth about his family and past. Revise what you have written thus far and be sure the conflict each character is experiencing is obvious, as this is one of the first things producers and directors will try to identify.
Set your word document to have a header on the right, .5" from the top, that includes the date of the latest revision of your screenplay. Set the font to Courier, size 12 pt. Set top, bottom and right margins at .5", and a left margin between 1.2" and 1.6." These specifics are important for writing screenplays that stand out, as producers receive poorly formatted screenplays regularly and appreciate one that conforms to industry standards.
Write the scene heading for each scene in all caps, preceded by INT. or EXT. to indicate whether this scene is inside (interior) or outside (exterior). The heading should state the exact location and time of day of the scene. For example: KITCHEN - EVENING. Center the name of each character, with their dialogue left-justified. Any action should be written left-justified as well.
Use present tense when writing the action (non-dialogue) text of your screenplay. Present tense means the event is happening now, i.e., "He looks at her," rather than "He looked at her." Use active voice instead of passive voice to create a strong script. An example of passive voice is "The car door is slammed shut" as opposed to the active voice, which would be "The car door slams shut."