Billy Wilder, the filmmaker behind classic films such as Sunset Boulevard, The Apartment, and Double Indemnity lists his top 10 screenwriting tips in Cameron Crowe's Conversations with Wilder.
Here are some of Wilder's screenwriting tips:
1. The audience is fickle.
2. Grab 'em by the throat and never let 'em go.
3. Develop a clean line of action for your leading character.
4. Know where you're going.
5. The more subtle and elegant you are in hiding your plot points, the better you are as a writer.
6. If you have a problem with the third act, the real problem is in the first act.
7. Let the audience add up two plus two. They'll love you forever.
8. In doing voice-overs, be careful not to describe what the audience already sees.
9. The event that occurs at the second act curtain triggers the end of the movie.
10. The third act must build, build, build in tempo and action until the last event, and then—that's it. Don't overstay your welcome.