Practising realism and hair with special emphasis on eye and skin shading.
The albedo of the skin and the details were done inside ZBrush (Polypaint) while additional maps (roughness, transmissive, etc.) were subsequently created using Substance Painter.
The hair is simply FiberMesh geometry thrown at Marmoset (no low-poly). :)
Polycount Thread: http://polycount.com/discussion/168634/girl-hair-study-toolbag-portrait