I love these tutorials from Pat Imrie, they are always concise, and well presented, and this one is no exception where Pat provides an introduction to using BlendShapes in Maya, offering a great overview for how Maya uses BlendShapes, creating BlendShapes in Maya, and also provides some tips for using BlendShapes in Maya.

A quick tutorial explaining the basics of the Maya Blendshape node

Pat Imrie goes over the options for BlendShapes in Maya, explaining what the options do, and their implications when creating Maya BlendShapes and also suggests some creative possibilities and uses for Maya Blends.