This may seem super simple, but alot of people get it a bit wrong along the way, and is the way I always set out my low poly for the animation/rigging teams. Try to keep it as simple as possible really.
This is using my latest male and female base mesh. Designed to have all artists, riggers, animators and texture artists in mind, and available through my artstation store now.
https://www.artstation.com/crazyfool/store
It utilises all the major edgeloops needed by animation departments to support systems like FACS or traditional rigging/animation requirements.
Whilst also being super artist friendly with even topology and anatomically based polygroups with realistic proportions that make it easy to sculpt on. Including correctly sized eyeballs with base eye textures for look development.
It is also fully Uved in a way that gives you maximum resolution where needed.
These are the case studies I created after 8 hours on each. Looking forward to detailing next, and breaking symmetry.