Watch Others at the Table as They are Watching You.

You have to pay attention to what is going on at the table if you want to make it deep into a tourney.
When out of the hand spend your time looking at the players and their actions rather than texting and tweeting. You can pick up a lot of information by observing the betting, tells and other behavior. Are they nervous, acting fast. Do they suddenly stop talking? You can be sure that the serious players are watching you.