As far as Bitcoin and other SHA256-based coins, someone else had already pointed out that GPU's are not profitable in the least. It is doubtful you will even pay off the graphics card before the thing dies. Those coins are dominated by dedicated hardware called ASICS, and breaking into that game at this point is a bigger gamble with potentially bigger payoffs -- especially if you wait and see if BTC gets as high as some people suspect it will. Risk vs. Reward and all that.
With cash-in-hand, it's been said numerous times that trading is the most profitable way to make money with cryptocurrencies -- and they are right, but it's also highly speculative and you can stand to lose a lot very easily this way. Diversify, and don't invest more than you can afford to lose.
Mining altcoins can be quite profitable, especially if you don't have to pay for electricity. But the best bet is to figure out the hashrate of the graphics card you expect to get, such as an R9 290X will get between about 720KH/s and 980KH/s.
This is just an example. Estimates for Scrypt-based coins can be found here, on the Litecoin Hardware Comparison Wiki:
https://litecoin.info/Mining_hardware_comparisonOnce you know the hashrate you can expect, you can look at a site like coinwarz.com or wheretomine.com to calculate profitibility of a card. Be warned though, a lot of them fluctuate wildly throughout the day. You are probably best to start off with an established coin such as Litecoin, Worldcoin, or Digitalcoin and solely mine that. Litecoin in particular has been very predictable in its exchange rate to BTC lately.
Though, honestly, I would suggest you learn a thing or two about basic PC building before you consider trying to put together your own rig. There are countless guides on google on how to build a Scrypt mining rig from scratch (google "Litecoin mining rig guide"), and for the most relevant results you should probably click on "Search Tools" and limit your search to the past 1-6 months. Aside from that, the folks on reddit.com/r/buildapc will be helpful in learning the basics if you don't already have them down.