I don't use GC... I use Poser 9 and (could be wrong) but I seem to recall that GC is only in the Pro versions? Even so my renders look good as they are and I would need to learn even more to make what I know compatible with GC...

@latexluv: I usually make the Eccentricity about 0.400000 and the SpecularRollOff about 0.200000, with a Reflectivity of between 0.600000 and 1.000000... Also with the lights it usually works to lower the "specular" to completely black on regular lights and have only one specular light with solid white... this way it minimizes the amount of shinyness the lights in the scene cause. If only one spec light is not enough then on the "Main" light, (the light that fills from the front) up the "specular" to a medium-to-dark grey which seems to be equivalent to making the spec value about 0.5 or so...

EDITED: to add a few more suggestions...