I try to, but the bigger sizes that I need are always the first to go, lol. I have found some great clothes on clearance racks though, for great prices.
The prices of clothes are marked up so much, it's ridiculous. A plain Tshirt might cost $30 just because it's from the Gap or something and it has a brand name on the tag. I can buy 2 metres of selvedge cotton for as low as $8 and make my own shirt in an hour.
I'm cheap, I head straight for the clearance section. However, I don't like to look tacky. If your willing to dig, sometimes you can find something awesome on clearance. Also 8 times out of ten, a lot of stores have really cute clothes that are off season ( swimsuits in winter, long sleeves in summer) I usually prep for the oncoming season with clearance items.