Light above anything else, makes photography. A great photographer is not only a master of his or her camera, but also a master in controlling lighting.
One of my favorite photographers, Matthew Jordan Smith, which many of you may have seen teaching on CreativeLive, explains the amount of control and detail he puts into his lighting approach. In this video, Matthew discusses different lighting scenarios, metering ratios, and controlling light.
One thing I want to point out is shooting against a white seamless. Like Matthew said, the light that is hitting the white seamless should be between 1/3 to 2/3 stop over your main light. Once you start getting 1-2 stops over your main light, the white seamless becomes a light source and will in turn kill the contrast in your image. His method will help you get crisp photos without overblowing your background.
To learn more, check out the video!