Bill Scheft has been writing for David Letterman for years (as well as being a novelist), and in the video below, he gives a behind the scenes look at what it's like to write for the show, including how much input Letterman has, what he's looking for, and what jokes you shouldn't do. I wonder who wrote the Sarah Palin joke? (You can see Scheft most nights standing on the stage off to the right.)

[via TV Tattle]