Sculpting and ZBrush pass
When all the pieces were modeled I export them to ZBrush as separate subtools and began sculpting step-by-step: modifying shapes, adding more details - wrinkles, scars, hair, veins, folds etc.
For the body parts I used layers for the scars, veins and skin texture. At the final stage my .ZTL was about 60 millions (without weapons) (Fig.07 - 10).
Low poly model
After the high poly model was modeled and sculpted, I exported the lowest level of all of the subtools to OBJ one by one.
When all the pieces were in Maya, I grouped them into blocks depending on my low poly needs and started retopology using Maya's standard tools for polygonal modeling
When low poly was done, I continued with UV mapping inside Maya (Fig.11 - 12).
When the low poly model was done, I did some preparations before exporting pieces for baking. Parts that could potentially cause bugs when baking Normal , Cavity and Ambient Occlusion maps were separated from each other.
So every low poly piece was exported as a separate object to make the process of baking easier and much more predictable. By the way, before exporting meshes for baking I did triangulation to avoid Normal "shifts" in the future. Doing this helps the geo look much cleaner with and also don't forget about hard edges at surface critical angles! (Fig.13).