Graphite ( pencils) are gray and shiny and go from H to B ( from Hard to Bold/Black).
H scrape the paper and are fine, and B are oily and more messy.
When you draw, hold the pencil far from your hand for an outline, then start "scultping" with the B pencil, your crevasses, your shadows and mounts. If you have a face to draw, imagine a structure made of legos. Imagine putting that structure on the table and you looking directly above them. You are the sun. The lego closer to your face will have more light.
Start by making small squares and start blending, adding, try to create a balck and white rainbow. Take pictures and put them in black and white, study the differences of this gray, whit the one next to it. Take a piece of paper and try to find the exact tone of the tip of the nose with your pencil, then fold it, and try to get the cheek, or any other place that looked similar. Once you achieved the right intensity and tone, open your paper and compare.
These are your swatches.
Watch a sitcom. Observe how the light falls on their faces illumination only a fraction. take a screenshot and turn it into black and white. See?
Train your eye to see better and interpret, better.