Don't be afraid to experiment, add a different media, see if it enhanced it. It's never wasted, you learn just as much from those that don't work.
Charcoal powder, an old hog brush to get the basics done on the paper. stops you getting putting in detail too early.
Refine as you go adding a little detail, this gives yo a better idea if things are in place.
Add to this then start to bring out some lighter areas with the eraser.