In a few of the photos the skier is facing away from the camera which is fine on some occasions but here id recommend against it. Also for the first try to get closer so that it is more detailed and as before mentioned try to find better lights since it really improves the feel of an image. for the last one I'd say that I agree with erikK in that you should try to get the whole shot. Personally my fav is the last one its a cool hit and the skier stands out from the image.
Final tip is to make sure you got the correct lighting, it looks sooooo much better when you can see all of the details in the snow.
If you can jjust correct those little problems they will be great :)