1. Play your table
Don't worry about how many tables are left or who has got what in chips. Keep focused on beating your table, and your table only. You should feel like your goal is to be the chip leader at the table at all times, and in order to achieve this you have to be able to take calculated risks. You will never win if you always play safe.
2. Adjust your strategy
There is not just one type of strategy that works best in the long run. You have to be able to play in many different styles and with many types of opponents in order to be successful. Your play should not be conceived beforehand; instead, you should adjust your game after your opponents and then play accordingly.
3. Play to win the tournament
You should have no fear of getting knocked out by making a move that you think is correct. All you can do is play your best and hope to get lucky. You should always play to win the tournament rather than to simply finish "in the money," as this attitude will most likely land you up on the bubble instead. When its close to the money, the strong players will run over the players who are just trying to last. This is one of the most important factors in good tournament strategy.
4. Don't change strategy just because the field is big
Your game should not be affected by the size of the tournament, only the players, the blinds and antes, and the chip stacks at your table should influence your play.
5. You have to get lucky
While all the top players agree that skill is the most important factor, they all believe that you have to get lucky to win a big tournament. Your big hands have to hold up more often than they should and you can't afford to get unlucky more than a few times.