[…] Question: Where to start when developing a story?. […]

Bill Martell's notion that you should always begin your outline with the villain's plot and goals is a point of view I'm starting to come around to, at least for thriller/action/crime type movies. What makes sense to me is the notion that if it isn't for the protagonist, the villain's plan should succeed perfectly. For example, Hans Gruber's robbery in Die Hard. Of course, there are exceptions like The Matrix (although in this case, from a writing POV I'm starting to view Agent Smith as a hero of sorts... someone who's trying to save the Matrix), but in general I think it holds true.