Charcoal holders are helpful as far as controllability is concerned. I suggest drawing on grey pastel paper with vine charcoal for the darks and white chalk for the lighter lights. Save the chalk for last. Canson Mi-Tientes pastel paper, Flannel Grey, works well. Use the smooth side, as it actually has more "tooth" than the rough side. Ignore details until you're satisfied that the large shapes are indicated correctly, working from the general to the specific, large to small. Much practice will carry you past the unfamiliar stage.

Charcoal pencils, as you've discovered, do not erase well, so are not good tools for beginning a drawing. They can be useful for darkening the darkest darks in the later stages of a drawing's development, after the need for erasing has past, but they are really less than ideal even for that purpose. I prefer Wolff's Carbon Pencils for that.

With grey paper, the accurate judgment of relative degrees of light and dark is easier than on white paper. The tone of the paper can be left to represent middletones, so you can get good results more quickly.

Keep practicing. All the best sculptors can draw, and it has always been that way.

Virgil Elliott