there are so many variables that you didn't address. What type of games are you interested in? And at what levels? Do you want to maxamize your bonus? Or do you want the softests games? How much are you going to be playing?And the list goes on and on.
It seems to me that there is a lot of info out there and site reviews available. Instead of posting all the answers to these questions, why not just read TPs reviews, read some of larger site pokerroom reviews (although a little outdated, I recommend the reviews on flopturnriver). And then pull the plug on the site that tickles your fancy.
If you are putting in $50, I would go to a site that pays you a 100% bonus, play 2-4 tables of $0.05-$0.10 limit poker in a tight, aggressive style. You would be playing over your bankroll (should have $30 per table, but if you are tight aggressive at these levels you can play a little overextended). I strongly recommend Ed Miller's book on micro limit games. It would really be worth it to deposit $30 and spend $20 on the book if you are on a budget.
I'm going to try and attached an excel file of starting hand requirements from the Miller book. Seriously, at these levels, just play the chart preflop. And if you hit the flop continue to press. There is no reason to try and get fancy against assclowns at these levels.
preflop-Miller, Sklansky and Mason.xls.zip