One of the steps for building a character (in this case with Maya) is to rig them. That is to say, putting the bones inside the characters and adding the controls to manipulate them. This is generally just for the body, and unfortunately only half the battle. The remainder that we have to worry about is the face, which in itself a whole other beast.
A beast that is tamed much easier with this wonderful book at your side:
This is a book written by Jason Osipa, which details and teaches ways to rig the face to have all the expressions you could think of. The best part is that with the CD that comes with the book, he provides you the examples seen in the book, as well as the mel scripts and resources to apply to your own character! You really only need to make the blendshapes, and then the scripts he provides plugs it all in for you! It’s a huge time-saver, and will really make your characters jump out.
You can pick it up through Amazon with this link: