I've thought about this a few times.  The easiest lowest risk thing to do, I believe, is mine a CPU friendly coin like Quark coin which you can do on virtually any computer.  Alternatively you could get a USB miner but I'm not sure that increases the ROI really.  Does it?.  Neither of these make you much money but you really don't stand to lose much.  I've also heard about people mining a different coin ever couple of days (which sounds really time consuming), with GPUs.  Supposedly if you do that with a bunch of alt-coins when they come on the market, some of them should in theory produce exponential returns.  You can use coinwarz to maximize your return.  I envy people with powerful mining rigs but instead I have chosen to spend all my money on on a bitcoin atm.  Mining is a very high risk endeavour but I imagine you could always sell the hardware to gamers second hand if it really didn't work out.  I typically live in rental agreements where electricity is included so it's an enticing idea.

http://www.coinwarz.com/cryptocurrency