Well here is what I would do considering the num of people in the tourney
100- 400 play normal just like it is a normal sit n go, playing good hands only though to build a stack off the less experienced players who will play A 6 in middle position, after there were already a raiser in first position. And say you have AK in early position, all you are up against is A 6 come up, if an ace comes up and still about 200-400 ppl left just push in all your chips, the less experienced player will call thinking his aces are good.
500-Infinity This is how i would do it, and it is very successful to me.
Early position AK, AQ, AJ, AA, KK, QQ, JJ, TT I go ALL in no matter what
Middle Position AT, AQ, AK, AJ, A9, A8,A7, or any pocket pair ALL IN
Late Position any pocket pair, anything with an ace ALL IN
Please take my advice because it works good for me. And I tell you, that you will become a freeroll expert like me, the one and only BUFFCLEMINS