FIRST TEN COMMANDMENTS
There are a huge quantity of very basic rules that you should follow that can help you avoid your screenplay becoming a quick pass from producers. Here is a starting list of some of these things.
While there may those "one in a million" stories where a producer options for a six figure sum a beginning writer's script that is filled with holes, but has a brilliant idea, this happening to you is about as likely, as winning the lottery. So, make your screenplay as good as possible!
1) Make screenplays between 90- 120 pages. Bind them with two long brass brads and put on card stock covers. On the front you can list it's WGA registered (my agent even has me do this with every synopsis he sends out for me), but don't put on stuff about nobody can reproduce it without your consent, etc. Producers know that. It just makes you look like an amateur and the kind of person who might be prone to litigation. In the other words, the kind of person a producer runs like the wind from.
2) Don't give principal characters similar sounding names with similar spellings. In fact, don't even have two principal characters that start with the same first letter. Readers can easily start to jumble up who's who because they plow through so many scripts. Make your script easy to read and comprehend.
3) Don't have lots of insignificant characters that are all labeled things such as "Guy". It's really better if you can differentiate them by calling them BIG GUY, ANGRY GUY, etc. If it's a really insignificant role then I sometimes just call them BIG GUY #1 , #2 etc. But, you can't keep calling people who your principal characters run into by the same designation, GUY. It's confusing and when someone has to figure out how many people they need to cast it will take a lot more work.
4) Don't call your character one thing in your narrative and have everyone else in the script refer to her as someone else. For example, don't you call her JASMINE, but everyone in the world of your script calls her MS. SMITH. Again, it's confusing. And when it comes to confusion, it's easier for a reader to just decide it's a pass. Plus, if you piss your reader off, that doesn't help your chances either.
5) Don't put in the scene blocks INT. HOUSE - SAME. In particular, if you do this a few times, it gets confusing what the original scene was. Then, the reader has to angrily turn back a few pages to remind her when it is. And forget about when somebody has to budget this thing.
6) Don't have dialog that runs 8-10 lines. If the character must make long winded speeches, then break it up with narrative so it doesn't freak out the reader.
7) Same thing applies to narrative. If you write half page blocks of narrative, the reader will just skip it and go on to the next dialog. And if you had something vital in there, the reader won't know. She'll just think you're an idiot that left a big hole.
8) Keep dream sequences and flashbacks to an utmost minimum. If you do a masterful job, they can work wonderfully, but it's a high risk thing to do. Most of the time, they're not needed they and just seem like cheap exposition from an unskilled writer and are generally frowned upon.
9) Don't have characters tell other characters with dialog what we just saw happen in a previous scene. There's only a hundred pages. Besides the fact that it's dull as hell, you don't have the space!
10) Avoid stereotype characters as much as possible: "hookers with hearts of gold", "rugged tortured cops who lost a loved one or a partner", etc.