You can hook up with anyone you meet off of any site.
I have tried match, Okcupid, and A4A.
I only have A4A right now, and dont really trick with it much. I chose that site because the 4 people I met from the other ones said they all had A4A too, and that everyone has A4A, and I see no point in doing something "clean" because it costs money.
So meet people for coffee, see if there hot or not, go back with them, and (most importantly) BE SAFE.
That one is very important.
Also, if you have a smart phone, I may suggest grindr. The best lay I had was off of Grindr. He was a 6'1" 200lbs Brazilian personal trainer, not an ounce of fat on that man. His tool was 9" too, which isnt bad.
So yea, for good sex, Grindr is best.