Any sites you recommend?
Strategy?
Well, if you're into sports betting, FrueGreads and I are running a tipster competition, sponsored by DirectBet.eu, where you can earn up to 3 BTC in prizes, plus tips - and, even if you don't reach the top prizes, you'll still get a guaranteed 0.03 BTC free bet (or a 0.09 BTC free bet, depending on your starting bankroll). Also, it's free to enter, and you can start with as little or as much of a bankroll as you feel comfortable betting with. Here's the thread, if you want to check it out:
https://bitcointalk.org/index.php?topic=1159253.
You can earn allot with gambling but the risk is that you also can lose allot with the gambling and that is not 50-50 sometimes you will lose more and sometime you will win more besides you can gamble with poker you will have a nice rate.