You know who is the Master of Folds in Clothing? xuvrette:

She whipped my butt into shape! I still have a lot to learn but at least I'm better than I was! And thank you! You really you see the crap I made when I first started! You just have to keep at it, don't be afraid of critique and changing the stuff you make, and you will definitely improve in no time! You are really off to a good start already!

One tip I like to think about is to get the shape correct before adding the shading! It's hard to erase your shading each time you change the shape!