Whily Ed is crunching the code and literally compresses it like a singularity, I am having a fun time doing the morph targets and bone setup for our final character.
Creating morph targets means You actually model the expression of the face for a given situation (shock, awe, happyness, sadness...) and add it to a library, so that when You are animating the character all You have to do is open that library and play with some dials (simplified version of a very fun and intuitive process).
If You are doing character animation, morphing is usually a step after the basic animation is done.
First You animate the overall body motion, then You add so called secondary motions, which can be either morphing or dynamics (cloths, chains, armour, guns...).In an ideal case though, the body motion would be sufficient to achieve what You want.
The less You need to achieve an animation, the better.Its like Jean Claude van Demme versus Sir Anthony Hopkins.Where Van Demme needs a dozen spectacular moves to impress, Sir Hopkins just raises an eyebrow and makes You shiver.
The trick in expressions is to make them asymmetrical and stretchy, as this emphasises in our case the comedy/cartoon element.
This is an example of an expressions chart I did for my diploma: