Updated Render - 750 Samples
It is amazing how the most simplistic renders are amazing! 
I like it, and 1000 cycles it usually all you ever need to render, maybe even less, I noticed that cycles only need to be higher for higher resolution images, but yeah, this looks great. Great Modeling of a Skull. I am not good at anatomy, so I admire work like this, like other stuff I seen on this site.
Great texturing as well, I just looked closer to the image.
You could try adding a second light ( maybe a rim light on the Viewers Left side of the skull ?! ) to define the shape a little better. That aside this already looks very nice, keep them coming 
This is already a 3 point lighting - the warm and cool lights are just very subdued. However, I moved them slightly closer to the subject on the 2nd render.
ty- TGA
^ is that a ui joke?!?!
I like how you used the gui screen as a ground plane.