Hey wow, the last one is really cool. It looks unfinished, however. Looks like you seem to have a firm understanding of how light sources should interact with the subject, just not how to appropriately change the color; This video can help more than me trying to articulate it.

Again, it looks unfinished, so I'm not sure whether to tell you about texture on everything except the skin. The shoulder piece takes up such a large portion of the image, and it's close to the head.

As for the other two, the hands really throw me off. Try using your own hand as a model for you to visualize the anatomy better. Most things wrong with the first two can be cleaned up through practice with an intention to improve.