The Tiny Protagonist has a good interview with Javier Grillo-Marxuach (a writer/producer on Lost and many other shows), talking about how he got started and the craft of television.
I like his explanation of keeping the reader engaged:
You know what a Gilligan cut is? It’s how on Gilligan’s Island, the captain always goes, “I’m not wearing the chicken suit!” and then bam –- he’s wearing the chicken suit. A Gilligan cut is very much a SMASH CUT TO. So if I have two scenes that are sort of languid scenes of characters, you probably don’t put a CUT TO. But if you’re doing a Gilligan cut, then you put a SMASH CUT, and instead of using a slug line, you turn your slug line into the captain wearing the chicken suit, and you describe the setting later. So you do things like that really to try to get the reader involved with the prose so they don’t just go from dialogue to dialogue.
To get a sense of his style, check out Grillo-Marxuach’s site, where he’s posted a bunch of his scripts, treatments and pitch documents.
He also discusses one thing I’ve come to appreciate over the years: screenwriting does get easier with practice. What you lose in youthful energy you make up for in finesse:
I find that, what experience gives you is craft, which means that when inspiration fails you, you can still build a pretty workable set of bookcases, even if they’re not the prettiest bookcases. And an ability to cope, mostly to cope with the psychological rigors of the job.