Hey there, I think the advice on the anatomy given from Dan are well put. I would like to maybe add a couple of things related a bit more to the color. I think in general you did a pretty good job already. One thing that I think is hard to grasp when getting started with rendering realistic skin, is to understand that the skin is somewhat translucent, (more and less in different areas) so often there will be more or less red or blue from underlying blood vessels shining through. I think you did a good job seeing it in the neck area, but for example in the shadowy areas of the lower arms you went more for an "orange-y" shade where I think there would be more blue in there. Generally your shadows look very warm toned where in the reference they are more desaturated. Maybe you can keep an eye on those subtleties of the differences in hues in the skin. One last thing I noticed is that your highlights (mainly) on the shoulder look a lot more "sharp" than the reference, though maybe that was your intention. Generally, the sharper the edges of a highlight, the more shiny a texture will look, so in case of a wet skin that would make more sense, dry texture of the skin (in non oily areas) has more diffused kind of edges. Anyways, I hope this makes some kind of sense and helps you out a litte. I still struggle with skin myself, but these things are advice I have learned along the way.