Things you can do while waiting for a tournament to start:
Go get a caffeinated drink, it may improve your quick reactions!
Make sure your chair is adjusted correctly.
Do some finger exercises for dexterity bonuses.
Realize that you probably won't win.
Clean your mouse for optimum key-response time.
Do a little dance.
Play solitaire, if your deck of poker isn't buried somewhere in your apartment. Mine are.
Sit in silence while you reflect upon your past and consider the games you'd be playing.