Exactly. Take note of the shape of the head in David's edit (nice job, btw). If you want to give a sprite (or any character even) more personality and dymanics, make their form interesting. You have to think of it as if you were molding something out of a lump of clay, sure, a circle is a primitive type of head, and it gets the point across, but if you start to exagerate different parts and/or block off different defined sections it gives it more personality.