The different stages of a poker tournament
Playing in the early stages:
This is the time to build up your stack and gain a strong position in the game. The best way to do this is playing patient, solid poker. In the beginning of a tournament the size of the blinds (or antes) usually won't have a big impact on your stack. This means that you should wait for strong hands and make the most of them when they come. Risky plays are not recommended in this stage of a tournament.
Playing in the middle stages:
In this stage of a tournament you generally have to pick up the pace and play more aggressively. The stakes are rising and your chips will slowly drain away if you don't get involved in the action. Naturally you have to take more risks in these situations. However, many players stick to their tight approach in the middle stages and that is something you can capitalize on. Aggressive plays will win you a lot of pots against hesitant opponents. On the other hand, if your rivals loosen up, you should play more conservatively. If you get someone trapped the pay off can be great. As you can see the way the other players act becomes increasingly important in the middle stage of a tournament. If you've been observant earlier in the game you will have gathered a lot of useful information about them and you can use bluffing strategies. Who can you bluff? Who calls a lot? Who should be treated with respect? The decisions you make will greatly influence the amount of chips you have going in to the next stage of the tournament.
Playing in the late stages:
When you've come this far the size of your stack becomes a very important factor. If it's big and you're closing in on the money you could play passively and watch other players get knocked out. Then, when the prize list is just a few places away you should speed up again (this can also be done with a medium sized stack). This change of pace is likely to be respected by your opponents. In general you should only go up against players with smaller stacks than you, since they will be afraid to get knocked out. This strategy will help you steel a lot of pots and further strengthen your position. Players with big stacks should be avoided unless you have a really strong hand.
If you have a small stack and the tournament is coming to an end you have to take more risks. You don't have the time to wait for a really good hand since your stack is disappearing rapidly. If you don't get involved in the action the players with larger stacks will bully you around and you will soon reach the point of no return. In fact, it's better to risk it all with nothing than just fade away without making a stand. Aggressive play is your best chance to really get back into the tournament. This means betting or raising instead of just calling. If you hit a really strong hand you have to try to make the most of it. Slow playing is always risky, but also a way to win really big pots. If you lure one or more of your opponents into betting you could quickly be back in contention.
If you are playing a home tournament, you may want to consider playing a rebuy tournament should you wish to keep playing once you are all out of chips.