At this point it is hard to earn money mining. Although many are anticipating the release of ASICs, I have my doubts they'll see the light of day for at least a year (if not more). That said, it doesn't hurt to just set up a miner to give you some 'trickle-in' BTC, just don't expect to make a ton of money.

Also, be really, really careful with your wallet. Your wallet is golden, store it safely, and securely, and as much as possible, offline.