Moo0 Window Menu Plus 4.1 Key Key ((LINK))
First, select your undeformed mesh and create your basis key. Go to Editing (F9) window and go to the "Shapes" panel. Press the "Add Shape Key" button. Enter and exit edit mode to set the basis key. Then create your first key Key 1 and name it "M". Enter edit mode and if your character's mouth isn't already closed (some people make them that way) then close it by carefully selecting the faces and loops around the mouth. You will usually use Size-Z plus a bit of grabbing and shifting to achieve this. Don't forget to include the faces on the inside of the lips or the deformation will be unpleasant. When you're happy with the shape, exit Edit mode and there you have it. Your character can now say "Mmmmmm" whenever you like. Test it by moving the Shape Key slider back and forth but make sure to leave it at zero before making more keys. (If you made your character with a closed mouth then you can just add the new "M" key then enter and exit edit mode to set it.)
Moo0 Window Menu Plus 4.1 Key Key
Go to the Timeline Window. This window seems to have been largely overlooked in previous documentation yet it provides the basics for timed animation plus a few other goodies to make your animation life a little easier. Here you can turn auto-keying on and off at will (you'd normally go to the hidden User Preferences window which is a pain and easy to forget), navigate frames, play and pause the animation in the 3D window, turn Audio Sync on and off, set the start and end frames for the animation and set frame markers. This last feature is the key to our project.