I feel like the shading is too dark on the right side of the face, it looks like a different skin tone. I’d make it lighter and closer to the original skin color.
Also, if I would think of where lighting is coming from. ( front, behind, left, right, ect. ) Make sure if one side is shaded, that the areas that are on that side are also be shaded. If that makes any sense.
This is assuming that the face has a shadow, but it might not be.