To make this i used shaders to better see how topology moving. i made two joints. the jaw one looks like it may be able to be moved to the right a little. to start skin i bound head joint to mesh. i keyed jaw joint at an extreme (it started with weight 0). flooded lower lip verts to jaw joint. Then i flooded weight 1 most of chin area to jaw joint. After that when collisions happening with neck, i moved timeline back to less extreme jaw open and i used replace with 0.5, and 0.3 trying to see how falloff so neck not colliding with jaw too much. after prelim i used smooth tool.
Hope this is helpful.
Check out Todd Henry's Accidental Creative. I first learned about project management ideas from reading his work. I saw this book when I was checking out Jason Schleifer's blog awhile ago.
A couple study tips. Is to take screenshots of excellent wire-frames reference (check out earlier post Jonathan Paine (isculptmaquettes), Brian Tindall (hippydrome), Joy Johnson (njoydigital) have excellent examples to study) for certain areas of the face like the lips only, or the brows only, or the jaw only. Then try to model those.