Just to see if you've been paying attention for the last few weeks, we're going to have a little quiz. Below are four different situations: all No Limit Holdem tournaments, but different chip counts.
To hammer home that stack sizes are more important than hands: in the following coups, your hand is always A♥ 8♥.
1 You have nine big blinds. Everybody folds round to you in the last seat before the button.
2 You have 25 big blinds. Two players have folded and the action's on you.
3 You have 50 big blinds. You are in the big blind; everyone folds and the small blind moves in for eight big blinds.
4 You have 40 big blinds. Everyone folds to your button; the big blind is an aggressive player with 20 big blinds.
OK. Have you decided what you'd do in each case? This is what I would advise:
1 Move all in. Your stack is getting low and you have to shove while there is still "fold equity": an ace is a good enough excuse.
2 Fold. If you raise, you can't take a re-raise; calling is horrible; you have too many chips to move in. It's only a weak ace, throw it away.
3 Call. This guy is looking for a chance to shove with anything (see 1) and you're probably in front. If not, meh, you can afford it.
4 You can't raise; the big blind will move all in with a wide range and it will be very uncomfortable. You can just about shove, if playing aggressively. But it's better to just fold.