You get a bundle of tickets for various freerools, so you play these and try to cash. There is also a sign-up bonus, which is another bundle of tickets. To claim the sign-up bonus you need to react within two weeks after opening your account, which I unfortunately did not. Its no big deal for me though, since the value is only 8$ or so.
888 also have weekly freerolls reserved for players from specific areas, they have daily "spins", where you can win a freeroll ticket, and they have freerolls for people leveling up. So people loving freerolls will certainly find a lot to like about the site.
Every sunday for instance there is a 1.000$ freeroll called "battle for Scandinavia" reserved for players from Norway, Sweden, Finland and Denmark. Last sunday there was about 400 entrants, so this is essentially a 2,5$ MTT, which players from these countries get to play for free.