For starters, I would just not bother, It's too volatile and difficult to get any sort of ROI on your equipment, For one gpu, Say a 7990 will make you around 0.02BTC a day, If difficulty stays at it is (which it wont) the card will pay for itself in about 2 years assuming you have free electricity, And the card survives that long.

Personally, I would just put your capital you want to invest, And just buy BTC, The value will go up quicker than you ill be able to mine it.

If you really want to be a miner to support the network, I suggest FPGA's, Slightly more expensive but a lot cheaper to run and maintain.