Learn to have the patience of a monk and have a really big bankroll, especially in you are going to be playing in large fields. Cash game variance can be brutal sometimes, but large field tournaments are 10 times worse. They are basically and endless stream of losses interrupted by an occational big win, when you end in the top 3-5. In between you will have many smaller cashes, but these are not enough to pay for your buyins, so most of the time the bankroll is going south.
As others have said, you need to be a bit more conservative in tournaments to preserve your chips. However that does not apply, when you can put pressure on other players by going all in. So as stacks get short, tactics like re-jamming or even open jamming become very important. There is a huge difference between being the guy pushing, and the guy calling, and one of the biggest mistakes in general is calling to much, when it put your tournament live at risk.
Also there are antes in tournaments, so as stacks become short, blind stealing and other non showdown winnings become extremely important. When stacks are short, people tend to fold a lot to even small bets, much more than they do in cash games. So you want to use, what Daniel Negreanu called the "small ball" method. Lots of small open raises and C-bets, and you will see, that people just fold a ton, because they dont want to put in 20% of their stack just hoping you catch you
bluffing or improve on some marginal draw.