[AWBenson]

Pretty board question, huh?

A very simple outline: In the vertex modeler, select the faces that you want to mantipulate in a group (like the mouth and it's immediate surroundings). Create a target area for this selection. Create a morph target from this target area. You should see the rest of the model disappear leaving only the target area to work on. Reshape the model to form the pose you want. Repeat the creation of new morph targets from the target area for each morph you want.

Do note that each polygon can only have one target area. So you can not have the eye lids polygon covering the area of the mouth while the mouth area is it's own target as well.

Through practice, you'll learn how to break up your models into proper target areas. It helps a little to think about muscle groups while you make them.