There is not much you can do about the hand, except from adding proper shading, but personally I would try to give him gloves instead, it would fit the santa idea you're aiming for and would fit the model better, since I guess the standard model has gloves on its skin, too.
But you really need an idea for those horns. Since I guess it's teamcolour part, you cannot alpha them out and I fear, even if you could you would get strange looking wholes in your model.
I suggest you to change it into part of his beard.
How to do that ?
I guess you should considerate taking a look at olofmoleman's tuskarr skin:
http://www.wc3c.net/showthread.php?t=90527
Apart from that it looks really nice for a first skin. Maybe some more folds on his clothes and a red nose, like he went through a could winter night, would look nice, too
EDIT: Taking a second look, I suggest you to use some stronger black shading at some parts with opacity of 30 - 50 % for example at the buckles of the shoes and on the wooden stuff, and the plant at it!
Keep it up!