Well, my first thought is this, I think your technique is looking spot-on! Particularly the right arm. My gut tells me your shadow tone is too "brown" for this piece though. I would go with a color that has maybe more Paynes gray or black as a base in it for these shadows. It looks as if you have used maybe raw umber as your dakening color and it comes off a bit brown. I don't know if you have laid in any highlights yet or not, it could use a brighter highlight if you have. I think other than the color being slightly off a bit, your technique is looking very promissing. HTH,
Jay H.
OKC