Learning to use shapekeys

Following the tutorial "Creating an Advanced Face Rig - Part One" I learned how to use shapekeys and played around with this model by Norby again.

It's a start anyway. Smiles are easier than frowns. Eyelids are tricky. Brows are easy.

If you are following the video, there's a tricky bit (reflected in the comments) where he forgets to mention the use of "New Shape Key from Mix." He implies that pressing the "+" key in the Shape Keys menu will create a new Shake Key from whatever mix of shapekeys is set. Actually, you have to use a special button in the drop down menu to do that, as such: