5 tips on how you can use charcoal
Making Charcoal powder
using vine charcoal
using charcoal over graphite
using fixative to add tone
using brushes to blend

Making Charcoal powder
making charcoal is a nice way to add tone to a background.
using vine charcoal
vine charcoal while it cant hold its own point for long is very nice for starting lines. it can be erased easily and is very useful when starting a drawing.
using charcoal over graphite
graphite can be used to achieve gray tones and charcoal can be used to achieve dark tones. graphite while it can hold a fine point can be reflective so I like to use charcoal for the darkest tones!
using fixative to add tone
fixative can freeze the work you've already done you can then add tone to your work by using charcoal powder.
using brushes to blend
I like to use brushes to blend soft tones it also is good for preserving the paper.