They stretch from the eyes to below the nose. Use the horizontal line you first drew for the eyes to line up the top of the ears. They will end between the bottom of the nose and the mouth. Eyebrows tell a lot about a person's mood. A gentle arch over the eyes should do for a relaxed face.
Most people draw the neck too thin.
Start at the ears and gently curve in then out again. If you have room on your paper you can draw shoulders or part of the shoulders. Make the shoulders wide enough so you could fit another head on each shoulder. You could stop now if your subject has no hair. But if he or she does, remember where the hairline is.