Starting from scratch I would say 888 is the best place to build from $0, since you get some free tickets to some
freerolls when signing up, which can be used to build up to at least $5.
If you want to invest a sum of money to get started quicker, Pokerstars is a good option. At least when I signed up they had some good bonuses for your first deposit, in forms of tournament tickets. These are the only two sites I've signed up for though, so you should definitely look at some other sites to see what you like best.
Also stay active in this forum, post a lot of quality posts, and after a month you could apply for the Freeroll Club, where Cardschat hosts some juicy freerolls for you to build your bankroll across plenty of different sites. Check out what is needed for access into the Freeroll Club in the Cardschat.com Freerolls sub-forum.
Good luck and have some fun getting into
online poker