As of writing, I'm about to start the third of my classes, but so far I've discussed the findamentals of basic character design. The thing I stressed most was to know your character inside out, in both personality and appearence. I got some very interesting examples from my class, and had everyone pointing in the right direction in what to try next. I also encouraged them to try making model sheets of their characters' expressions and how proportions can play a role in the style of a character. (I got them to draw as much as possible during the week, before we get onto backgrounds and comic book layouts.)
This following piece is slightly more advanced; I didn't teach this bit (much) on the first day, as one would be expected to have a basic idea of how to design a character. I'm pushing the method a bit more here.
During my Visual Language class at animation college, I was suggested to go more 'abstract' in making concept work. Abstract art, as far as I can remember, is to look at the subject and observe it's colour, texture, structure, etc as individual pieces (rather than the whole subject as a figure/object), and re-create the subject using one of those themes. It may be more elaborate than that, but bear with me.
I scribbled down abstract shapes of emotions: Joy and Sadness. I made some emphasis on tears, hanging posture and timidity for Sadness. For Joy I lashed out some perky bubbly shapes, smiles and glee all around. I even included stickmen for posing the emotions. The colours were quite obvious, but in the end I feel they maketh the characters.
For me, the personality and activity of the character matters to me more than the final look. Personally, there's no point in making an extroverted, lively, sporty character and then go and hide her over-active body (language) in bulky robes or restrictive outerwear. (And NO neutral poses there!) From the abstact sketches, I made patterns and symbols from them afterwards.
What was I feeling here?