HI! First of all, thanx a lot for your comments on my DA, I thought the best thing will be to post some observations on you art, though I really believe the only way to properly comment on any work of 'traditional' art is by watching the original, since the scanner kills like 20% of the actuall quality (says someone who's trademark is using glitter and metallic watercolor, and that's invissible on the screen).
With this drawing you did a great job capturing the idea and show that you're actually a bit familiar with perspective. The only mistakes are, actually, common flaws that everybody makes and that can be corrected with practice and the acknowledgment of them.
First of all, judging by the pressure you had on the crayon, and the movement of the lines, you kind of didi it in a hurry. Relax!! Enjoy!! Any good drawing can take even weeks to be completed depending on it's format (most of mine are less than a letter sheet and take about one week with watercolor, twoo days with ballpoint pens, and like a month or even more when I use color pencils). One thing that always helps me when drawing these guys, is to think that I'm like 'enjoying myself with them' whenever I'm drawing.
Second, you have the idea of proportion and movement, but it's hard to get it just with your mind (no matter how clever) Using photographs or drawings as reference for the poses can be quite helpful. What leads us to a small detail while using reference and even when drawing using only your imagination:
Draw what's there, not what you think it's there. That's basically the principle of it all (and, trust me, it's a pain in the bum) Once you get it you're on the other side.
And last, for now, shading. I can't see too well for what i tolds you about scanners but I think you're mking another common mistakes, which is shading with a darker tone of the same color. Human skin can be shaded with blues, greens, violets, and some black on the darkest areas (note that this colors should be applied softly and in layers alternating with the base color... that's the main reason for point number one) even if you're aplying strokes like you did in this drawing, the idea is to blend the colors and create a tridimensional effect. As for fabric, you've got the idea of folding, but you must learn a bit about the weight of each fabric (and so do I) sheet is a fine material and, in this situation, it would stick a bit more to her body.
... Sorry, I'm getting to long, but I think you're smart enough to learn how to observe and draw things a lot better!! Besides, you remind me a lot of myself and that kind of pulls my picky nerve. Keep on working and I expect your next piece to throw this one out of the window!!!