1. The Shape One way to start is with a realistically proportioned head. Just a simple, egg shaped oval divided vertically with a line so everything ends up symmetrical. A line to mark the eyes should be half way up, no higher. The line for the nose half way between the eyes and the chin; then one for the mouth about half way between the nose and the chin.
2. Exaggerate The trick to this style is exaggeration. Now that you have the start of a normal head, there are a couple major changes. First, exaggerate the shape of the head by sharpening the chin so the jaw tapers down abruptly from the eye level. Then the eyes: Unlike a normal face where the eye line marks the middle of the eyes, the eyes are stretched down to a little above the nose. An easy way to block in eyes is with lines for the upper and lower lashes, and a rectangle for the iris.
3. Add Details Start cleaning everything up and adding the details. Simplicity is part of the trick: a small mark for a hint of a nose, keep the mouth small, with a little shadow to suggest the lower lip. Give the lashes some flare and a downward turn and the end. The pupil should be elongated and black, the iris somewhat shaded, and there should be a highlight (on the same side of both eyes). Add simple lines for the eyebrows, and you can block in the hair.
4. Clean Up Clean up any stray lines, and add the neck (keep it thin). The bottoms of the ears should be about level with the nose. The hair should be very exaggerated--think big: If there is a part that curls up, it should curl way up. Don't draw individual hairs, think of hair as volumes that can be defined.
hope this helps smile