Pencils!
You only need three pencils for this type of drawing: an HB or 2B, a 4B, and an 8B. Or thereabouts. “B” stands for “black” -- B pencils are soft. We use an HB or 2B to set up our drawings, a 4B for mid-range tones, and an 8 or 9B for darkest darks. That’s it!
There are many different brands that are interchangeable. Right now I am using Staedtler Lumograph and like them. What you don’t need is a cheap set of 21 pencils ranging from all of the Hs and all of the Bs. You will be better off buying three better quality pencils of the desired softness. You can buy them individually at an art supply store or dickblick. I like this set — six soft pencils in varying degrees of softness.
Hard, or H, pencils are necessary for blending pencil drawings. If you are in love with pencil drawings, check out this article on what the H pencils can do for your drawings.
If you have pencils, what else do you need?
Erasers! Sharpeners!
Sharpener. My recommendation is do not waste money on plastic sharpeners. The metal ones work much better.
Erasers. There are three different kinds in the photo above: the white one is vinyl, the tan one is a gum eraser, and the grey one is kneadable. I find the gum erasers work very well to erase big spaces of wrong drawing. The white one is nice for erasing smaller parts of a drawing. And the grey one, the kneadable eraser, is nice for erasing on watercolor paper because it is the least damaging to paper. You can knead it to make a clean spot so you don’t spread graphite all over your paper. And, kneading an eraser can also be stress-relieving. Here is a set if you want to try all three.
Drawing Paper. And finally, you might want to invest in some proper drawing paper, 60-70 lb. The paper does not need to hold up for water media, but it should hold up to much erasing. Drawers who are willing to keep erasing until they get the drawing right will progress further with their skills.
Pencil drawings are a wonderful way to improve our drawing skills for painting. You can focus on the set up and values, erasing and repeating until you get it right. Setting up a drawing this way also helps us complete our paintings because we can work out the drawings details and values in the pencil drawing. When we get to painting, those decisions have been made and we can focus on color.
Remember what a student once told me: Value does all the work, and color gets all the credit. Use the range of soft pencils to achieve darker value. Your 8B or 9B is for your darkest darks.