Things that stood out from a couple of interviews with pro comics I recently watched/heard. I'll paraphrase...
Jerry Seinfeld: "The best part of being a comedian is getting to hang out with other comedians."
Jon Stewart: "You need to develop an internal barometer about what you think is good or bad. Don't fall in love with the audience."
Tim Conway: "Say it once, it's funny. Say it three times, it's less funny. Say it 19 times, it's hilarious."
Patton Oswalt: "Always go too far. Going too far turns ordinary into an event."
Patton mentioned Louis CK's "Why?" bit as a great example of digging deep on a single premise. It starts at around 7:00 in during the clip below:
