I'm reading through a slew of synopses for a jury. Most of them spend way too much on setting the opening scene, as if the writer was working his or her way into the movie.
If you're writing a pitch, do not tell me visual details. Do not tell me any details that aren't story elements. Don't tell me what the extras are doing. Just tell me the story.
These synopses are theoretically for a project that hasn't been written yet, which accounts for the "working their way into a story" feel. It's okay to work your way into a story (though it is less professional than breaking the story down first). But then go back and trim.
I often write a 10 page outline in order to distill a five page pitch. I need 10 pages to figure out what the story is. But I don't deliver ten pages. I deliver five.
Work out the story first. Then write the pitch.
That doesn't mean write the pitch with the story on your lap. Many synopses I've read for other juries seem to have been written with the script open. Page by page, we work through the script. It makes for a stilted read.
The best pitches are written off the top of your head. Anything you can't remember off the top of your head stands a good chance of being unnecessary. If you're truly stumped what happens next, you can check back to what you've written -- but the odds are excellent that there is a big gaping flaw in your story right where you lost your train of thought. If at all possible, fix it before you send your synopsis anywhere.
You should write your pitch, ideally, as if you are in a room talking with a producer. You have five minutes to tell him your story off the cuff. Write the words you would say if you were talking to a human being, in the same room, with the same level of detail. You wouldn't tell us what the extras are doing, would you? (You might use a bit of hype to sell a moment. But only the most arresting moments of the movie -- the "money shot" if you will.)
A pitch should sound as if you are in the room, selling the story.
Another way to look at it is: write your pitch as if you are selling your story to a rich uncle who is going to invest in your movie. You wouldn't tell him what the extras are doing, or how the light slants in through the drapes. You'd sell him the story.
Another way to look at it is: write your pitch as if you are telling the story to your 10-year-old nephew or niece.
A pitch is not a work of literature. It is you, in the room, selling a story.
Simplify, simplify, simplify, and never be boring.