Not a pencil - a stick of vine or compressed, or a stick of conte - something you can turn on its side for broad strokes at least an inch wide. Also, a chamois is good for drawing, too (not just for erasing).
The best thing about charcoal ( a hunk of it ) is that it can be used to draw and paint. Save the pencils for contour practice. It doesn't lock you into making one kind of mark or using one kind of technique. You can draw dark on light and right away reverse that to draw light on dark. You can swab in slabs of shade/shadow with the broad side and, voila! Done, without a single line. I miss being able to do that with a tablet
I used to do the same thing, gesture drawing from virtual life. lol. It works very well. The big paper lets you put your whole arm into it. Once you get used to that, you feel every stroke coming from the pit of your stomach. After a while, it's not so much a matter of swinging your arm as swaying your body - it feels like dancing, or martial arts, as it should, since it's all about rhythm.
The movement starts in the core and works outward from there traveling along the arm, like energy running through a whip, or water through a hose. At different parts of the stroke there is the opportunity to inflect the line to give it character. This last part is easy to do with a brush or hunk of charcoal that has a pointed side and a broad side. Of course you can strip a pencil to expose the graphite core, which will enable a broad stroke. But for that you need a large core, because standard size cores will break when you apply even a little pressure on the stroke.
Which reminds me - graphite sticks can be a good compromise when charcoal isn't handy or when the conte isn't working well [ 1) you sometimes have to sand or otherwise abrade the side in order to get a broad stroke from it - sometimes have to blunt the tip, which can be so sharp that it cuts through the paper. ].
Dang! Natasha. I think I'm going to work with charcoal today. I miss it.