Establish what needs to happen in the scene. Developing a treatment outline will help to break down the script scene by scene.
Determine how long the scene needs to be. A ten-page scene, for example, would require ten minutes of screen time. If the scene is not important enough to take that much time, shorten it or cut it entirely.
Decide where the scene takes place. Film scripts scenes begin with a scene heading, or slug line, that establishes if the events take place inside (INT.) or outside (EXT.), then exactly where the action happens such as PARKING LOT or HOTEL ROOM.
Choose which characters need to be in the scene. Know the characters; make sure what they say and how they act are consistent with their personalities. Remember to always capitalize names in your scripts.
Write a "scribble version" that includes some details about the scene. Just write a few words about what might happen in the scene, and refer to these notes later when writing the full scene.