You've got approximately ten pages to establish three things to your reader or audience: (1) Who is your main character? (2) what is the dramatic premise - that is, what's your story about? and (3) what is the dramatic situation - the circumstances surrounding your story.
Know that you only got about ten pages to grab the attention of your reader or audience.
What's the best way to open your screenplay? KNOW YOUR ENDING!
Billy Wilder once remarked that if you ever have a problem with your ending, the answer always lies in the beginning. To write a strong opening, you must know your ending.
Executives read too many screenplays that they learn to tell within the first ten pages whether a script is working or not. They don't have time to hope the writer did his or her job; he either set up his story or he didn't in the first thirty pages.
Shakespeare is a master of openings.
What makes a good ending? It has to work, first of all, by satisfying the story; when we reach the final fade-out and walk away from the movie experience, we want to feel full and satisfied. (carthartic moment) And it's got to be believable.
Don't be attached to any single shot, scene, or sequence.
Your ending may change as you write the screenplay. Go with it. But that doesn't mean you should begin writing without knowing your ending.
The ending comes out of the beginning.
Questions to ask yourself when writing the beginning: Does it set uour story in motion? Does it establish your main chatacter? Does it state the dramatic premise? Does it set up the situation? Does it establsh or set up a problem that your character must confront and overcome? Does it state your character's need?