You can't expect to make any significant amount of money off of freerolls. Generally speaking, they are only for practice, as they provide somewhat competitive play due to the real money payouts, without the risk of having to pay an entrance fee.
The problem with trying to make money off of freerolls is that their entrance numbers are usually so high, and their payouts are very low. Even if you play extremely well, you still need to get pretty lucky to get paid, so you shouldn't count on them as a way of making money, though if you do play them somewhat regularly you should occasionally be able to hit a payout to help build a starting bankroll.
The League freerolls on
Pokerstars are particularly good for this if you play them often enough, as you will accumulate leaderboard points for good placements and can get a pretty substantial payout at the end of the month if you place top 100. And of course, there's also the Cardschat freerolls, which have the luxury of much smaller fields and much higher payouts than usual for club members.
