1. Buy Bitcoins
2. Hold
3. ? ? ? ? ?
4. Profit (well, more than if you tried mining, likely)

With the difficulty ever increasing, all mining equipment have a limited life span, possibly measured in months.  Personally, I'd buy the coins outright and wait for them to increase in value instead.  They have to go up because they will become more scarce.  I've stopped GPU mining, for obvious reasons, and didn't enter the ASIC bandwagon...yet.  Their ROI isn't worth the risk and many have already been burned by it.  So, for me, they have become scarce.  I'm sure many others are in my boat.