value study crazy

I am thinking about doing value studies to  put into my portfolio- so I attempted this  figure drawing in sketchbook pro- just using the pencil tool for sketching the outline and the paint brush on medium opacity for the fill colors- I am trying to keep monochromatic so I can practice on identifying shapes with tone only... I determined that a clean line and great silhouette is the start for an impressive value study- well I have to get back to finishing the shading on my comic assignment of finishing pages for a writer in our comic group in preparation for Detroit Fan fare