What kinds of shoes were you using before? Rather than the typical gym users trainers you'd be better of in boots. There are a ton of good squatting shoes but they're expensive. Have a look at Nike Romaleos
For squatting, you want to use minimalist shoes. Squatting in bare feet is actually best but obviously that's not the best idea in a gym - very easy to get a foot fungus.
I personally use wrestling shoes. They are kind of like slippers with grip on them.