Step 2: Don't get a head of yourself...
Cut a strip of fabric that will be wide enough to match the roundness of front of the mouth. Make it long enough to cover your arm and an additional length for the top of the face.
Cut a portion for the top of the face from that strip of fabric.
Attach the longer piece to the bottom of the mouth.
Add the shorter piece to the top of the mouth.
Sew so that when turned out the seam will be hidden.