After playing freerolls for a really long time I've learned a thing or two about them and I'll gladly share here. The problem with them is that unlike cash games above 1c/2c, tournaments both freeroll and big buy in ones have a much larger level of variance. And this is infinitely more true for freerolls. A lot of people think, "hey it's free I can do this every day, why not just try to get as many chips as I can" and they'll do the craziest moves you've ever seen. Those types of players are completely and utterly unpredictable, they might be holding AA or 72 their playstyle is probably going to be the same aggressive shove/fold pre flop all in. Those kinds of players are the ones you need to watch out for.
And the problem is, in the early stages of freerolls the majority of players are like that. And I'm going to tell you that IT MIGHT NOT ACTUALLY BE BAD. Don't stone me to death for this, I'll elaborate I promise. Freerolls are a HUGE HUGE gamble and having a big stack is paramount for you to get to the late stages when they actually start paying anything half decent. You have to make those really risky coinflip all ins just to boost your stack so you have room to either wait out those unpredictable players or just to have more wiggle room to outplay your opponent post flop if he's not one of those maniacs.
Now, I am in no way advocating you going all in with completely silly hole cards, but just bear in mind that openning up your range a bit at the start of a freeroll might not be as bad as you think.