12. It's Based On Pre-Existing Material
Um, how do we say this nicely? You just wasted a whole bunch of your life. It's never, ever a good idea to write spec scripts based around pre-existing franchises, characters owned by large corporations, or to attempt to write that "perfect" sequel to one of your favourite movies (unless it's for fun or is in the public domain). Writers are hired and appointed by studios to write those sorts of movies when necessary. As good as it is, nobody will ever agree to read yours.
11. You Haven't Fixed All The Typos
It sounds ridiculous, but just one typo is enough to turn pretty much anybody who reads screenplays for a living off of it forever - even if it's the next Casablanca. We know you think you've got rid of all the typos, but you really haven't. There are still typos in your script right now. Two or three of them, even. Have one more look. And then another. And then another. And then...