Hi, Klebnor. I agree with Bar-code, once you have gotten used to Carrara, Poser will never be good enough. 
With Carrara, the better the lights: the slower the render, but the results are awesome.
What is a "better light"? In the C6 render room, the options for skylight and indirect light give great results. If you are importing a scene with the lights already set up, the default render settings are good, but also try a render with "indirect light" selected at 100% (also check for transparency beneath it!) It makes a huge change in the quality of the "realism".
If the render is too bright, turn down the strength of all the lights in the scene.
C6 has a default "distant light" present in all scenes. You can delete this light after you import your Poser scene.
If you have trouble importing your poser scene, try resaving it after deleting the "ground" and the camera.
Have fun.