You nailed the face, and the hair looks good too! I can see where your concerns are routed in the shape of the hand (wrist area, finger length) and the shading of the shoulder. Chin up, though! It all comes with practice...and dude, chalk pastels have a bit of a learning curve on them...I could only pray something I was fucking around with, using only chalk pastels, would come out half as good as this...its WAAAAY out of my comfort zone, and the only way to expand on YOUR skills as an artist is to push the boundaries of your own comfort zones.

That said, Mission Accomplished!

Keep it up dude! It looks good. Even if you hate it, never delete this; for it will serve as a testament to how far you've developed in retrospect...and shit, if you don't like how THIS turned out? You're aiming highly for yourself. Settle for nothing less, and keep on developing and improving.