Unbiased render engines really give a realistic boost to lighting and realism, IMO.

I would say in particular order:

1. Lighting

2. Render Settings/Engine

3. Textures/materials

4. figures

I just went through getting a little more realistic look in a carrara render.  Materials are not that great, and I am not a huge fan of the render engine...but given the correct lighting, it really came out nice!

It would come out even more real in Lux, I believe. 

In lux with really good textures, good lighting...very real

Make the person morph very realistic...now your talkin REAL!