Players who are sitting at the final table of a tournament should stop thinking about winning pots and start thinking about winning stacks. This is also a pretty good way to approach the start of a tournament as well, but not collecting stacks at that point is not vital. Players who go into heads up play with an overwhelming chip lead will win more often than they will lose. That is why you want your opponent's entire stack instead of just hanging on by winning the odd pot. So part of winning stacks is convincing your opponents to push their entire cache of chips into the center of the table.
You want them to bet their entire pile of chips on your terms, not theirs. If they start off a hand by going all in before the flop, and you are not holding some premium cards, challenging them might be a bad idea.
Projecting weakness is always a good way to get another player all in. They want your stack as bad as you want theirs, so if they think they have a reasonable expectation of coming away with your chips at the end of an encounter, they will go all in.
Having your bluffs exposed is another good path to the chips your opponents are jealously guarding. If you make a couple of runs, firing off one and two barrels on a bluff, just to fold when you are called on the third barrel, the other folks around the table will get the message that you can be put off a pot during the last betting round.
Once that has been established, and you do get a workable hand, your opponents won't be too concerned when you bet and raise during the first couple betting rounds. In order to scare you off somebody is going to push their entire stack into the middle of the table. At that point, your trap is sprung. You call their bet, flip your cards over and expose a legit hand. Chances are, because they thought you were bluffing, they had lowered the value of the cards they were willing to play against you. If all goes well, their chips are now yours.
Good Luck!

