If there are re-entries allowed, then I will play extremely loose and aggressive - the object of the early levels is to build a big stack.
However, most
freerolls do no allow re-entry into the tournament... and therefore, my play style is quite tight, I will only play 10% of starting hands, basically high starting pairs and good Broadway combos (preferrably suited). If I can see a cheap flop with suited connectors, I also try to play those too (mainly as a balance for my premium-heavy range). But I won't play 65s or 87s if there's a 3-bet, I try to call and limp in just to see a flop and hope I catch some good
equity.
If I do make it to the middle or late stage of the tournament, this is when I begin to play more aggressively and try to steal the blinds more - mainly because the blinds during the early levels isn't worth the risk of stealing them, they are very small, and it only makes sense to try to steal blinds once they become larger later in the tournament. Also, we have much better reads on players at our table in the later stages of the tournament, we have been able to observe their play style for many hands at that point, so we know who is likely to fold to the steal attempts and which players don't like to fold so easily.
Hope this helps.