One, don't wait for inspiration, just start the damned thing. Two, once you begin, keep on until the end. How do you know how the story should begin until you find out where it's going?
The Last Airbender is an agonizing experience in every category I can think of and others still waiting to be invented.
[Marlon] Brando was the only guy who could step out of that shadow at the end of that movie and be worth the wait.