Choose a screenwriting software (script formatter) to write your screenplay. There are many options available, ranging from industry-standard software like Final Draft and Screenwriter to free software such as Celtx. You can also use a web-based script formatter free of charge. Some writers use add-ons for their word processors, though this is more difficult than using dedicated software. All of these options work the same way, with TAB and ENTER for automatic formatting, and any of them will create an industry-standard screenplay.
Write only what you can see and hear on the movie screen. Too many beginning writers try to place character thoughts in their screenplays. Anything that can't be shot on film will be thrown out. If you need to show that a character is angry, write action that shows us. Make him do something that can be filmed. "Eddie SLAMS the door on his way out" is correct, as opposed to "Eddie is mad because she doesn't understand him." You could also write dialogue in which Eddie says, "You don't understand anything about me." Action and dialogue are the main elements to focus on when you write a screenplay.
Write in absolute present tense. Never use past tense. The line should read: He draws his Colt .45 as he enters the house." Never write "He entered the house as he drew his gun."
Make character names all capital letters when they first appear in the script. Never capitalize characters who don't have speaking parts. Minor characters may be named by a trait rather than an actual name. Example: BURLY COP, HEAVYSET CLERK.
Capitalize character names for dialogue. Your scriptwriting software will do this automatically. Write action scenes and dialogue in sentence case. Try to keep action scenes and dialogue minimal. Between three and five lines is acceptable. The more white space on your script, the better. Large blocks of text tend to cause readers to skip the action or dialogue, which is not good when you're trying to get a screenplay purchased.
Direct the camera without using camera directions such as CLOSE ON or PAN or PULL BACK TO REVEAL. Unless you're the director, you should focus on the story. Instead of writing JOHN's POV, simply write "JOHN sees a man enter the building with a gun."
Describe characters and settings as briefly as possible. Choose only two or three details to bring out the essence. Too much description breaks the flow of the story. For characters, give name, age and a brief identifying feature or two. Example: "Jenny, 20s, pretty in a girl-next-door sort of way." This leaves room for actors looking for a role.