If your figures are looking plastic it is likely the textures, not as much the lighting. Mainly highlight and shine. There are many lighting options in carrara. Alot of variety in presets also. Play with the lighting types in simple scenes. There is some info on 3pt lighting in the manual. Check it out. Also it covers the texture room.  Turning off the ambient lighting in the scene is important. The default is 20%. You can add some back in or use different colors, but that would come later after you get a feel for it. Play with the different kind of lights to see how they look. HDRI and a combination of distant or sunlight can be a better way for outdoors.

No need to think outside the box....
    Just make it invisible.