Some knowledge I picked up from this 1975 animation special issue of Film Comment magazine:
1. Weight=Believability
2. To show surprise, connect whites of the eyes OR raise one eye OR make one eye square.
3. Be mindful of primary and secondary action.
5. Characters are the multiplications of our own foibles. All humor is based on that fact: the recognition in others, in a multiplied form, of something that we ourselves are capable of.