Artist, Illustrator, Life drawing Instructor at Seneca and Humber Colleges in the Animation and Illustration programs, Werner Zimmerman offers this advice to aspiring character designers.  Get to know your character.
'Make your character do things that are totally unexpected.  To bring him/her/it to life they have to be full of life: make them move beyond your comfort level; make them feel every emotion you do (especially since you are the main model for any of them).  Make a list of expressions and portray your character, your character's body (gesture) and your character's face in each expression on your list; do so from every possible angle.
Only then will you know your character. '
Werner Zimmermann
farmer Joe, model sheet (1)Have a look at Werner's book art website
and see more of Werner's drawings and paintings on man4art.