I don't really impulse-buy shoes.
I had a beautiful, beautiful pair of Manolo Blahnik satin high-heeled mules. They were painfully lovely. But satin is impossible to take care of, and although I never stained them or anything, just with general wear the fabric began to split (leather stretches out slightly). I will never buy satin shoes again, no matter how lovely.
I try to avoid suede, also, because it's so hard to take care of. Wash your hands and accidently get a few drops of water on them -- and they are practically ruined!
I like camel and black leather shoes. Slingbacks and pumps are great. I avoid anything too strappy because I like my shoes to work for both day and night. I don't own many pairs so when I buy, they're usually quality shoes that have to do double-duty.