Clothing folds, and motion (btw: I hate shoes...and feet. I never learned to draw feet 'cause feet squick me the wrong way. Don't ask.)
Remember, cloth is affected by it's different weights, movement, and physical force (ie: bending). Hair is the same dealey. Thick hair's gonna do something different from curly hair is going to do something different from thin hair.
I actually drew this flipped backwards. Fact: your eyes adjust to your own mistakes. Things that others would see you'll miss, so hold your paper up to a bright light (with the back facing you), look at your painting upside down, or flip your image along the horizontal axis (you can even do it in MS paint). Best advice I can give any aspiring artist.