Use screenwriting software. Two popular screenwriting software programs are Movie Magic Screenwriting and Final Draft. The programs feature shortcut elements that make it easier to type. If using a screenwriting software, skip to step 3. Otherwise continue.
Set the word document up with 1-inch margins all around. Change the font to Courier New. This is the standard screenwriting font because it provides the proper spacing for words and letters.
Start off the screenplay with "FADE IN:" right-aligned on the top corner of the page.
Write every scene with an opening heading or slug line, detailing the scene's location and should consist of multiple elements. First, write either "EXT." for exterior or "INT." for interior, followed by the actual location. Type a dash and then either write "DAY" or "NIGHT." Avoid descriptions such as "Sunset" or "Dawn." A complete slug line would look like this: "EXT. STREET MARKET--DAY."
Write a new slug line for every location change. For example, if you have scenes in the same house, split up each scene by rooms. "INT. JOE'S HOUSE--LIVING ROOM--NIGHT" or "INT. JOE'S HOUSE--KITCHEN--NIGHT" are two different examples of how different slug lines are written for different rooms. If the whole movie takes place in one house, you can eliminate the "Joe's House" section of the slug line.
Type out action for the characters. You should never start or end a scene with dialogue because screenplays need to be visual. Action is always written in the present tense. Avoid words like "is" or adding "ing" to actions. For example "Sam is running" would be changed to "Sam runs." Read over all your action to phrases to clean up the writing.
Limit sections of action to three or four lines. If the sections become too cluttered, the action becomes confusing. Simply create a new block of action after three lines.
Introduce new characters with all capital letters. For example, "The door swings open. JIMMY, 28, runs in as sweat drips from his forehead." Even minor characters and important animals in the story should have capital letter introductions.
Center dialogue text. Type out the character speaking in all capitals, press enter and type the dialogue. To add extra actions, such as whispering or yelling, place the action in parenthesis next to the name. For example: FRANKIE (WHISPERING).
Write 90 to 120 pages for a full movie. Each properly formatted page of a screenplay represents about a minute of air time. The script should be broken into three acts. The first act should take around 30 pages, the second act should take around 60 pages and the final act should take 30 pages.
Rewrite and read over the script as much as possible to improve the story and the writing. Read the script out loud to hear how dialog sounds, check for grammar mistakes and make sure that a clear three act structure is present.