Hey! I hope this hasn't been posted already, et cetera.

I'm starting a project that'll need some heavy After Effects and I'm curious if someone more experienced than me has a strategy that I'm not thinking of. Mostly, this project involves motion tracking and a bit of animation.

Here's the project in a nutshell: In 2D, I plan to animate a talking cartoon head on top of a live action body. The shape of the cartoon head is perfectly spherical. I want the eyes/mouth to motion track separate from the head so that the cartoon face will mimic the angle of the live-action actor's face.

My strategy is to motion track the round head (just a static blue ball) on top of the live-action actor's head, while motion tracking the cartoon eyes/mouth to the live-action actor's forehead. I want the face to "turn" when the live-action face turns. I'll use a mask to keep the eyes/mouth from going outside the borders of the cartoon head.

I plan on putting markers on the live-action actor's forehead. What's the optimum number of markers to use?

I'm going to motion track the eyes/mouth to the forehead markers, while motion tracking the head to the actor's entire head. Does this sound doable? Is there a better way to accomplish this effect? I hope I'm getting the idea across. It feels like a pretty abstract thing to describe and I might not have all the terminology straight. Let me know if I need to clarify anything. I'd really love some help on this. Thanks in advance for not flaming me if I'm breaking some obvious rule.