I'll recommend Screenplay, by Syd Field, as one of my favorite resources. It doesn't help me with plots, characters, or word choice, but it helps with timing and pacing.
I know that I should have about twice as much middle as end and beginning.
To misquote Checkov, if I want to have a gun go off in act three, I need to write it into the room in act one. I know that I need to sometimes think of the chapters as a series of sequences strung together.
By knowing what's important to the Imginary Film Version of my story, I know what to put (and not put) in my written version.
-FredG