Using a mechanical pencil, I first sketched a simple contour shape of my hand. Then I took a paper stump and pulled the graphite shading giving form. If I needed to go darker, I scribbled graphite on a separate piece of paper rubbing the paper stump in it and then back to the hand. Or you can go back over gently with the pencil lead itself and then blending it out with the paper stump. I worked these both ways until I achieved the look I was hoping for.
Side Note: Have a putty eraser handy as it can be used not only for erasing areas you don't care for but as a great "tool" for adding highlights.
Also sometimes I might want a nice evenly shaded area but might end up with a spot or two that's darker than the rest.............take your putty eraser and shape one end about the size of the area that's too dark and then just lightly touch eraser over the spot. Many times it will lift just enough to make that spot blend in with the rest of the shading without messing up the tone you want (that's surrounding the dark blotch). If need be, gently "dab" the area again.
Done on cartridge paper:
Went with less lines for wrinkles on this next one........
Worked the finger and thumb in the same way.