I don't really have a pregame "ritual" but I only play when I feel good (not tired, irritated from my day at work...etc) I come home from work and throw the ball with the dogs for 20 minutes or so, talk to the wife...unwind a little then I usually play a 1-2 table SnG and hour or so before entering a large MTT to "warm up"
While I play; I practice chip tricks (unless the wife is working next to me, clacking chips irritate her after a while) take notes on other players or sketch. Lately I have been chatting on the IRC.