Of course we don't mean the poker sites will just GIVE you free money without doing something for it. They will, however, give you free money for playing a certain number of raked hands. So if you can play break-even poker you can end up WAY IN FRONT.
For instance, Party Poker offers a $200 bonus for playing 1000 raked hands (5x). This is just about the best bonus in the business. For that $200 free money bonus you would need to deposit $170 as the bonus is for 120% of your deposit up to a maximum of $200.
You play your 1000 raked hands and they will give you $200 for free. If you make some money while playing then that is also yours to keep. If you lose some money while playing then the $200 bonus would compensate for your loss.
It's a win-win situation so you really haven't got too much to lose and plenty to gain.