Buzzfeed has a lengthy interview with several of Hollywood’s top screenwriters that’s worth a look: How to Write An Awesome Movie.
Also worthy of your time is this Q&A with J. Michael Straczynski from last year’s Phoenix Comicon. His Complete Book of Screenwriting was the first screenplay manual I ever read. I still consult that book, which reads woefully out of date in matters of technology but remains timeless in terms of actual writing advice. If you can track down a copy, snag it.