Part a.
Tight sketch.
Based on the critique make any necessary revisions to your sketch. This may require research, taking photos for references, and redrawing your composition. Your final sketch should be clear and legible. You may draw traditionally with a pencil or if you prefer you can do this digitally.

Tight sketch for Rigoletto

Part b.

Add Value
Keep your sketch in greyscale. Add value to your sketch to help establish the focal points and foreground, background, etc. I suggest doing this digitally and creating a separate layer for your original drawing.

Tight sketch with value added digitally for Rigoletto