The gate keepers to Hollywood are Readers.  Few Producers or Executives will read the script until it has been vetted; and some don't read at all if you can believe that.  So Readers hold a lot of power unfortunately.  If you get a cranky one because they have a 100 scripts to read, they are just looking for a reason to deleted your script and move on. Your job as the writer is to not give them a reason.  Well lucky for you, I have a friend who works in Hollywood as a reader  She told me writers need to keep the following in mind:

Unique Voice and Style

A reader is drawn to scripts with a distinct voice. From your choice of words to your ability to provide a unique perspective and style can set your screenplay apart from others.  How you approach your story and how you move it forward is crucial.

First Ten Pages

You have to HOOK the reader right away. Introduce the main characters and establish the tone of the story. Not just readers but any Producer (that reads) will often decide within the first ten pages if a script is worth continuing. 

Compelling Characters

Characters move your story forward and the better they are written the more engaged your reader will be. They should be well-developed, relatable, and have clear motivations. Readers look for relatable well drawn characters that move the story forward.

Writing Visually (Vertically)

Screenwriting is not like fiction, you have to be careful that you're only presenting what can be seen or heard. Do not have exposition that is choked with blocks of text, write vertically meaning with brevity and movement. Instead of heavy dialogue and exposition, use actions and visual storytelling to convey information. 

Pacing and Structure

A script that flows and the pace moves it effectively helps to keep readers engaged. Follow the traditional three-act structure but don't be afraid to innovate within it. Ensure that each act has a clear purpose and contributes to the overall narrative arc.

Keep these things in mind and try to write a screenplay that moves and flows and engages, and you're halfway there.  Then the rest is up to talent, can you pull it off or not?