I went to the Orme Art Group charcoal workshop today. It was run by an artist called Jo Watson and she taught us various techniques. Here I used brushed on charcoal powder smudged with a rubber tipped tool. Then I used willow charcoal sticks which you put on in a random way, then smudge again to lighten the charcoal. Finally you add darker layers to add contrast but you can tone these back to the paper colour, either by using a putty rubber you can shape, to lift off a layer of charcoal, or you can use a mechanical eraser thar rubs off patches to make the drawing lighter.