>>5937513I have limited experience with charcoal, but I've collected a few tips:
Use vine charcoal first; crayon charcoal later (binder is harder to eraser).
To get darker values, the charcoal may need to be work *into* the paper. This likely will work best with cotton papers.
Some charcoals such as Nitram's can be sharpen to a fine tip, and use like a graphite.