Practice! Hands, Feet and Faces
It can be quite difficult drawing hands and feet from observation (especially feet) but with a bit of practice I found different ways to make it easier and to help proportions by drawing basic shapes first to angles and size then slowly adding more details.
I really like using different colours to distinguish light and shadow in a drawing, like in the last two images where i have used pink to show light and blue for dark, varying the tones of each to add detail.