I studied some facial topology and simplified my terrible rigging & stuff into something simple for the community.  And Zero Attribution too!  I like Zero Attribution stuff!
She uses mostly shapekeys for expression except for the eyes, which are a combination of rigging and the shrinkwrap modifier.

The shapekeys will cause a bit of jiggling on the back of the head.

Be sure to share a link with what you use it for, we'd all like to see!