Until you get to prizes, play only the best cards, ensure that you always had a positional advantage.
Many opponents play freerolls carelessly. Given the fact that in case they do not lose anything of loss - because a free tournament, they go all-in preflop, even with questionable cards. If you wait for a strong hand, it's easy to beat them.
If the card is not good, do not be nervous. Be patient and wait quietly, "his game", despite the fact that stacks rivals grow, and your not. It's not for long. Very soon you will "catch" the right hand, and the stacks of loose players perekochuyut to you.
The closer to the bubble-zone, the game becomes tighter. Maniacs and overly loose opponents have already departed. Those who remained, trying not to risk because of the unfortunate bad beat did not retire from the tournament in one step from the money.
Take advantage of this and play aggressively. Use your stack to pressure on rivals: play strongly against rivals who have less of your stack, but avoid harsh confrontations with opponents who have a stack more.
Good luck in the freerolls!