For table games, my superstition is that if I drink more, I'll care less about the 5.25% house edge.
Also, I think it is bad luck to not tip double for the first drink a new bartender pours. Especially at Mugsy's Bar in the 'Mingo when I'm doing the VP == free drinks deal.
I guess my only real superstition is in Texas Hold'em; I bet stronger with pocket 9's than similar 8's or 10's. They've been good to me before.