Never call all-ins by players who have about as many or more chips than yourself in the beginning of the tournament. Even AA loses. Call all-ins by inferior players when you have AA, KK, QQ, JJ and AKs.
Never bet on a fire flush; Only call smaller bets and inferior all-ins.
Never call large bets to get the last card in a straight.
Always bet or re-raise if you have the highest pair. That way you can tell if the other guy has something of value.
Try to get to the flop cheaply if you have suited and connected cards. They can win you a lot while high cards can lose you a lot.
Be careful when betting at a full table in a bad position. There's a big chance you'll get called by more than 2 players which makes it very hard to win.
Don't go all-in pre-flop if you have many chips. Just raise by doubling up the pot.
Always raise pre-flop if you have good cards - but don't raise too much if you want someone to call you. AA and KK are good to slowplay.