A basic problem, which isn't really solvable, is that the tones of the face are really flat and the face tends to look a bit plastic when it is worked on.
This happened because the face was in the total shade and, even if exposure corrected, there wouldn't be any micro-texture to make it look alive.
The image isn't all that sharp and that might be due to camera movement.
You were shooting at f2.8 1/80 and ISO 100.
The effective focal length is about 80 mm and you should be shooting at least as 1/125 or 1/150 to minimize blue from camera movement. You could raise the iso to 400, increase teh shutter speed and lower the aperture, thus giving you the benefit of a slightly deeper depth of field, probably sharper lens area and faster shutter.