“The most carefully studied 22 square inches in the universe,” is how the human face is described. Faces are intimidating to draw because we know them so well, and can detect the slightest distortion. But there are simple guides online to help you; here is one. The most surprising fact is that the eyes are at the halfway point between the crown of the head and the chin. Here’s my pencil sketch of a photograph I found on the internet. The placement of shadows shows that the light is coming from the right. It helps to have a good eraser!
