The replies here are very useful, thanks all.
Currently, I'm playing micros SGs to clear a 50$ bonus, but I'm considering moving to 5NL (2 tables). Actually, I'm playing SGs to improve my game, rather than to clear this bonus (it would take 2000 games to clear it).

Moving to cash games is a possibility, but to clear this bonus I have to generate $400 in rake to the site. Is it feasible starting from 5NL? Should I deposit more money in addition to the $46 and play at a higher limit?

I dont have a deadline to clear this bonus...so, I wonder how can this be done in a fast (and safe) way. After clearing this...I'll do some bonus whoring and I'll also ask for advice.

At this moment, only 3% of this bonus was cleared...so...it will take a while.