Don't pledge. It's a sorry excuse for meeting people, and once you do it, you're fucked with the same friends for four years. I'm a firm believer that greek life is a gigantic crutch. I am, in fact, in two greek organizations but merely for the resume boost if offers.
I really believe that making friends on your own allows you the opportunity to be much more discerning when you meet people and offers you the chance to encounter many different groups of people without the jaded mentality that greek life will surely provide you.