Tournament Play for Poker
Tournaments require an additional layer of strategy to what you can probably tell is already a pretty strategic gameplan. This additional layer is the blind, and how it increases over the course of the game. Early in a tournament, where you might start with 1,000 chips, you'll have to pay low blinds when they come around (such as 10 small/20 big). That means you have 1,000/20 chances to be involved in a hand, and with the blind amount considered the big bet, you've got ammunition to spare.
Blinds increase on a time scale, usually every six minutes in "Turbo" tournaments, or at 10 or 12-minute increments in regular play, and sometimes even longer. And as blinds go up, the number of big-bet opportunities in your stack decreases. So you have to be aware of your stack size as the tournament progresses. Sure, you might still be solvent an hour in, but if you haven't grown your pot, you're in danger of being forced to play weaker hands in order to make a move while you're giving away blinds. Tight play can be effective, but don't forget to be aggressive when the hand, position, or players suggest it's time.
What does this mean? If the four cards showing give you a flush draw and the bet is just, say, 50 out of your 1,000 stack, it might be worth making that call. Hit the flush on the river, it's likely you'll be scolded or vilified by someone playing top pair (it always hurts to get rivered). But the lesson here is that your opponent should have bet more to persuade you not to call his gut-show draw. (And you'll have a big chance to increase the pot size with a sizeable bet of three times the pot when you're in the flush position.)
Marginal Hands
If the short-stacked player goes all-in pre-flop and you think that you have a decent hand, it's often worth calling knowing that his shot pile means his marginal hands are likely to be overplayed. That player could be feeling that his A-3 offsuit is that hand to go in with, but your pocket pair will stand up very well.
Re-Buys and Add-Ons
Many tournaments allow you to re-buy if you bust out (going all-in and losing) or to pay a second entry fee to add chips to your stack. In low-stack tournaments, many players play overly aggressively in the early rounds, taking advantage of cheap re-buys in the hope of generating large stacks by the time the re-buy/add-on period is over. Usually these situations are a crap-shoot, and it is simply recommended to ignore them and find tournaments where players respect each other and the game.
Playing Short-Stack
The flip-side of calling a short-stack with a decent hand is to aggressively play a half-decent hand when you're in that situation. Almost any pair is worth going all-in with if you're about to be blinded out of a tournament. Similarly, an Ace-X of any suit is one to chase, luck is definitely a part of poker, get a glimpse of it, and you might head back up the ladder.
It's also easy to get overly aggressive when you're big-stacked. Loose play will shorten your stack and bring players on the brink back to the mix. Srteaks of good flops and draws happen (suprisingly often), and when you feel it's your turn, take advantage. But then take your foot off the gas when the cards decide it's someone else's turn! It's here that discipline is critical. Don't lose it!