TURN OFF THE LIGHTS
That's right. Sometimes great natural lighting means turning off the lights. Whether its in a natural light studio or getting ready room at a wedding, if there is window light coming in some where, I'm typically looking for other lights that I can turn off. Think about it like this, window light is a certain temperature (white balance wise) and strength, any other light you have on in the room (florescent, tungsten, halogen, etc) will be giving off a different color of light than the natural light coming in the window. That means if you have the window on one side of your subject and a lamp lighting the other side, you are casting two different colors onto your subjects skin. Hello, editing nightmare. Skin tone problems caused by mixed lighting like that are brutal to try to fix. To keep things clean and colors consistent, I turn off the extra lights in the room and open up the windows fully. I'd rather bring up my ISO higher and have a bit more grain (Cameras these days can handle it) than have color issues. If you don't believe me that a darker, window lit room is better than a brighter room with mixed lighting, test it out! You might be surprised by the difference!
In each of the rooms above, there was window light and a few other random lamps and lights on. I used to not make many changes to lights, etc on wedding days because I wanted to be a fly on the wall, but the truth is that these couples are trusting me to do what I need to to create the best images I can for them. Now, I ask the bride and makeup artist something like "Would you mind if I turned of these two lamps?" and once I do, I'm left with even, problem free light!
5D III + 35L
With dark red wood everywhere in the room above, I was already left with a tough time dealing with skin tones since the light was bouncing red light into her skin. To cut out any more problems, I turned out all of the internal lights and had back lit, facing a neutral colored wall. That means the light that came in from behind her (now the only light source) reflected that neutral color of the wall into her skin.