Over-worked?

I would have preferred doing this head study on red pastel paper but even my extensive supply of art materials didn't extend to this particular colour.  I am working from a photograph of the same male model again but this time he is in quarter profile.

I used charcoal pencil for the initial sketch, moving to soft pastels for the shading and detail.  His nose is not right and I struggled with the lips but I'm relatively happy with the skin tone and position of the head is not too bad this time. Although I feel I may have over-worked it - knowing when to stop is difficult!