I use three lights in my renders nowadays, as per Bagginsbill's instruction, as I have understood it.

1. One Infinite Diffuse, set to 100% with raytraced shadows and ambient occlusion checked.
2. One IBL Diffuse, set to 20% without raytraced shadows, and with ambient occlusion checked.
3. One Spot light, set at 50% without raytraced shadows, and with ambient occlusion checked.

Gamma Correction in render settings is set at its default setting of 2.4.

As for shaders, I set on all my characters and props, Diffuse, Specular, and Ambient to white.  The intensity of that white I adjust by setting the values.  Diffuse I set to 1, Specular I set to 0.010, and ambient I set to between 0.001-0.0001.  This way, light absorbtion is close to what would be seen in the natural world.
I also texture my figures with three sets of textures, one regular, one desaturated, and one desaturated and inversed.  The regular I plug into the diffuse, specular, and ambient slot.  The desaturated I plug into the diffuse value, specualr value, highlight value, and ambient value slots, and set its intensity at 0.500.
The desaturated inversed I plug into the bump and displace slots, and set their values at 0.010 and 0.001 respectively.

Gamma Correction aside, I consider the ambient occlusion to be the most important aspect for the improvement of my renders.
DPH

  STOP PALESTINIAN CHILD ABUSE!!!! ISLAMIC HATRED OF JEWS