World Light
To better view your lighting, it is a good idea to turn off the World Light. The World Light is a light applied to the world around blender so that you can see things in rendered mode if you don’t have your lights set properly. It is on be default and can mess with your 3-point lighting. To turn it off go to the World Properties palette and set the Strength to zero. If you don’t have lights se properly, things will go completely black. So, watch out.