This is actually a tough one to answer. I liked the reply above which stated, 'better to try to preserver your bankroll and increasing will come on it's own'. This is a wise statement for sure!
With $30 as your total bankroll, you may find it very difficult to even build it from there and you can actually count on going broke a few times (especially if you're playing 10NL with it).
It also very much depends upon what your personal preference is for games online (ie. is it sngs, ring, mtts...??). Personally, mine is mtts as this is where I learned how to play poker and currently have been playing for just short of one year. Alot of my initial play came in the form of freerolls
so mtt play just became more natural to me.
You could try your hand at micro stakes sngs but on most sites the rake is very high in them (tourney fees of 20 to 25%). Over the long haul it is tough to run with an +ROI of that much for you to even be breaking even. Also, the play in the super micros is super weak at best, with an assortment of 'no foldem holdem' players, some very loose passive trappers and some complete maniacs thrown in there as well. It can be quite frustrating to say the least.
I'd actually suggest that you deposit a bit more to your account if you're actually hoping to build a bankroll, or hit the freerolls for a bit in hopes of adding to your roll &/or at least seeing a bunch of hands for free.
Good Luck on your quest to 'double' up your account. You might just do so in the 10NL but then again, it's just as easy to go right back down to zero. Personally I'd stay away from 10NL until you had at least 20buy-ins in your account (or more.. ie. $200).
Remember too that ring game strategy, mtt strategy and sng strategy are all a bit different... sometimes ALOT different.
(if it's sngs that you end up choosing to play, I strongly suggest that you read up on some sng strategy material cuz most players who are playing in them play them very poorly and are unaware of what a 'winning strategy' consists of (ie. stay tight in early going,..as it approaches bubble, change gears, loosen up and steal blinds,.. also if stack is down, look to double up when you can.. and don't be too concerned with players who seem to be in just about every hand.. they will more often lose those chips as fast as they've gained them).