When using shading, it is always essential that the different shades by blended. Rather than dividing it light, darker, and darkest, it should be a single section of progressingly darker tones. The lack of a background tends to take away, but in this case it prevents the admirer from seeing the proper shape and depth of the art. Also, it's hard to tell what your trying to say. Something along the finality of death? Or, perhaps more toward the human fear of death? Otherwise, a good overall undertone.
