Skull and Face 5"x7" watercolor sketch

Still looking at drawing portraits with my students. We looked at what forensic artist do. By taking human remains they can create a reasonable likeness of what the person may have looked like. This was my made up attempt of sketching a skull and creating a face from it. My biggest disappointment is how poorly my drawing scan in. The colors and values are reproduced horribly. I have to find a better way.