Hi Alex,
That looks complicated; there is a lot going on there. And it’s a spherical Object, Mesh Spheres are a bit of a topological nightmare.
It’ll be mostly trying things out and see what works, like a puzzle. You will also have to take advantage of Smooth Shading, more than relying on Subdiv..
This oldie is great (you might have already done it): https://cgcookie.com/courses/introduction-to-retopology
