Start this stage by using some compressed charcoal to loosely add more tone to the darkest regions of the drawing (background etc.).
It doesn’t matter too much how you apply the charcoal, hatching and scribbling is fine.
Once you’ve roughly applied a reasonable amount of charcoal, start spreading and evening the tone using a large brush.
It may end up slightly patchy but that’s fine as you will be working over it more – this brushed layer just makes a darker base tone to work over (vs the white of the paper).
One the tone has been brushed, start going even darker with the compressed charcoal.
Make your application more even and keep the hatching closer together this time (as we won’t be brushing it again.
Once the background is sufficiently dark, you can start adding features that are in the darker areas (such as the sprig of leaves sticking out of the ham in my drawing).
Make sure that these dark elements are unified with the surrounding darker tones. It can be tempting to make them lighter so that they stand out by that will disrupt the major tonal relationships in the whole composition.
Finally, use your kneadable eraser rolled to a point to neaten up any areas of light tone that charcoal dust has been spread.
You can also use the eraser to add more detail to the edges of the darker shapes.