Well first suggestion start reading. There are sites such as Simplyscripts.com and others that have a database of produced scripts. Dialog is a lot harder than it seems. Characters, action, pacing, and everything are a lot harder than they seem. Formatting is easy enough to get down, especially since you can just copy techniques from produced screenplays.
You'll want to read from spec scripts and get to know the difference between shooting scripts and spec scripts since their formatting differs somewhat.
Then you'll want to learn the wonderful art of editing. The stage I loath the most. Since you have finished one or two I strongly recommend getting someone else to read it, get honest feedback and take a good objective look at your work. It's hard but you'll learn a lot.
Chances are (you may have beaten them, I haven't read your work to judge) it's not ready for submission. It took me several screenplays and working with small time producers to get close enough to take up some gigs.
Also there is a writer's strike going on. Hollywood is basically shut down at the moment. Now is a great time to really work on perfecting the craft.
Good luck.
6 days is the fastest, it did and still does need a lot of work, I recently wrote an action script on assignment in 9 days. It needs some tinkering but it's no bad.