First simplydraw a circle. If you run an axis from the top to its bottom and a line along its equator, you can already imagine it be a sphere instead of a circle, even without any tone or value. Divide the sphere into quarters to further aid in this imagination. The sphere tips in the direction that you tilt the axis. Now if you slice off the sections at the sides of the sphere, you will get the sides of the head. The equator line becomes the eye brow line (the position where you place the eyebrows, not the eyes) The front of the head is curved but not as rounded as the sphere, therefore flatten it out a bit and bring it down a bit to get the bottom of the chin. i.e., Mark a point about halfway between the eyebrow line and the point where the axis comes out of the sphere, that gives the hair line. Almost about the same distance below the eyebrow line, is the end of the nose, the same distance below that is the bottom of the chin. The top of the ear usually lies on line with the eyebrow line and the bottom of the ear on line with the end of the nose.