Never been a huge Mamet fan, but so many people swear by his lectures that I think I might indulge over xmas break ;)

Screenwriting classics like "Save the Cat" and "The War of Art" contain very simple truths: there are rules to storytelling, honed over centuries of human experience and cultural evolution. Knowing when to follow the rules, and having the confidence to break them, is part of that journey, and can be applied to virtually any creative endeavor ;)