1. Is it properly formatted?

2. Proper spelling and punctuation. Sentence fragments okay.

3. Is there a discernible three-act structure?

4. Are all scenes needed? No scenes off the spine, they will die on screen.

5. Screenplay descriptions should direct the reader's mind's eye, not the director's camera.

6. Begin the screenplay as far into the story as possible.

7. Begin a scene as late as possible, end it as early as possible. A screenplay is like a piece of string that you can cut up and tie together -- the trick is to tell the entire story using as little string as possible.

8. In other words: Use cuts.

9. Visual, Aural, Verbal -- in that order. The expression of someone who has just been shot is best; the sound of the bullet slamming into him is second best; the person saying, "I've been shot" is only third best.

10. What is the hook, the inciting incident? You've got ten pages (or ten minutes) to grab an audience.

11. Allude to the essential points two or even three times. Or hit the key point very hard. Don't be obtuse.

12. Repetition of locale. It helps to establish the atmosphere of film, and allows audience to 'get comfortable.' Saves money during production.

13. Repetition and echoes can be used to tag secondary characters. Dangerous technique to use with leads.

14. Not all scenes have to run five pages of dialogue and/or action. In a good screenplay, there are lots of two-inch scenes. Sequences build pace.

15. Small details add reality. Has the subject matter been thoroughly researched?

16. Every single line must either advance the plot, get a laugh, reveal a character trait, or do a combination of two -- or in the best case, all three -- at once.

17. No false plot points; no backtracking. It's dangerous to mislead an audience; they will feel cheated if important actions are taken based on information that has not been provided, or turns out to be false.

18. Silent solution; tell your story with pictures.

19. No more than 125 pages, no less than 110... or the first impression will be of a script that 'needs to be cut' or 'needs to be fleshed out.'

20. Don't number the scenes of a selling script. MOREs and CONTINUEDs are optional.

Why Not Hone Your Writing for Free at HubPages ?  A great community with superb feedback for writers.