Patricia,

It would be my own preference not to mix graphite with these other materials. I don't particularly like the look of hard pressed graphite. I don't like what it does to the surface and I just don't like the way it looks up close.

My preference would be to use a very light pencil (which is easily covered up) until my drawing was established. I would then commit to either charcoal or the soft black pastel chalk. I have had some success augmenting a charcoal drawing with darker values of pastel, but I can see no reason to reverse that.

I find that I can get a very wide range of values with black chalk. Not too dissimilar to what I perceive a sauce drawing to look like.