Back in the old days, when US players could play online poker, I did the freeroll to bankroll route on Absolute Poker. I won some small freerolls, grinded on microstakes, won some larger tourneys, and got my balance to about $1000. I cashed some out, transferred some to FT and PS, and have been in the money on all three sites ever since. Only deposit I ever made was $15 on AP so that I could cash out (can't cash out without a deposit).
Way I did it was to grind the micros, survive the grueling play at large freerolls, and then grind some more. Read everything you can about sound bankroll management if you really want to earn from that first deposit.
I am not doing this to earn a living (I have a full-time job and full-time family) so it is much more a hobby for me. But I'm competitive (mostly with myself) and have read lots of books, tried to be active on this forum (the best one there is, really) and signed up at training sites (DragTheBar is sponsored here and they are great: send a PM to dakota-xx for details and a free trial).