When we think of animation, all we want is to get our hands dirty as soon as possible and bring our characters to life. But if we do that, we'll soon face problems that could easily have been solved with some careful planning.

To model facial shape keys, for example, a good planning phase will offer a list of necessary facial expressions, so you won't face any surprises such as missing shapes at the animation stage. You will also have a clearer picture of what rigging features you'll have to build for your character; this way you won't spend too much time creating things that won't be used.