I do not know your skill level, so is hard to making suggestion. Luxus and Reality handle material different and I don't know what you are using.

You should see tutorial on how Luxrender materials work with whatever exporter you are using.

Luxrender is a physically correct system, so lighting and color of surrounding objects influence as in real world.

To gain intuition of scene you must do many mistaken ones to see effect of changes.

I do this one, changing hair color and face morph but keeping most skin texture and shaders.
I think change can be called significant.