Sorry in advance for sounding like an ass ('cause I will), but I agree with Feron. Not that this isn't/couldn't be a good piece on it's own, but as an attempt to achieve a better understanding of anatomy (of both the human body and clothing folds), the overly geometric forms won't cut it. It's far too stylized atm. The entire upper body, despite being wicked stylish, is very anatomically incorrect, and as helm mentioned, clothing/cloth falls and folds very differently from stark geometric shapes then it does from, say, a leg.
Overall, I'd consider finishing this piece as a stylized whatchamacallit and then starting a new one in which you work on your anatomy/clothing skills. Or, better yet, working on your folds and anatomy in traditional art, as personally I find pixel art to be a poor medium for learning the basics.