You've got game.
You've got players.
And you're looking for the DIP (develop in play) content that will steer the game forward.
What is signal and what is color? Players throw off a bunch of info within the course of a game. As things move along, what flags the GM to make a course correction? Well, I don't know to chat about it, and sometimes I don't know it when I see it.
Perverse Access Memory: Actual Play: Unearthly Session Two
The 20' By 20' Room: Developing Stories Through Play
The 20x20 comments by Neel are particularly interesting to me. The notion that I'm churning the elements tossed into the game by the Players feels like my Art with regard to gaming. They build routines and establish the worth of things, and I test those premises. Not break them, but allow a challenge or test where I can read if 'breaking' is an option or a timely result.
Sometimes, the trick is revealing a 'break' opportunity and seeing if the PC goes into it willingly.