GPU mining is the traditional and the best way.
The thing is, if you have a very bad GPU you might not make any profit. The electrial costs are going to be a pain in that case.
If you have a fairly decent GPU, you can still mine and shine but expect a really low profit. If you aren't worried about the electrial costs ( as GPU is running 100% 24/7 ) then you could mine very well.
If you really want to know how much exactly you could mine
Use a manual calucaltor - https://tpbitcalc.appspot.com/
OR
Run a Miner http://bitminter.com/ ( Run the pool's miner for few minutes, it would calcuate an estimate for you )