You could go forever without adjusting white balance—left on Auto, your camera will usually get it right. But sometimes you want to be in charge. Here are three ways to take power over white balance.
1) Use a preset WB. These settings are simple to understand and can be useful when shooting under multiple light sources, which can fool Auto. Use Tungsten (usually denoted by a light-bulb icon) indoors under incandescent lighting—it makes the colors in photos less yellow (i.e., cools them down). The Fluorescent setting compensates for greenish artificial light, warming up your shots. Cloudy and Shade settings will also warm up cool, blue tones.
2) Create a custom WB. If even a preset won’t do it in mixed light, make your own setting. Photograph a neutral gray under the light in which you’ll be shooting, and select this frame in the CWB mode. Your camera will “correct” it to neutral gray and apply the same correction to ensuing photos. Result: cast-free color.
3) Fix it in postproduction. If you don’t want to bother making adjustments while shooting, or if you got it wrong, there’s always hope. In Adobe Photoshop, use the Gray dropper in the Levels command or the one-click white-balance tool in any RAW converter to click on any area that’s supposed to have neutral color. The rest of your photo’s color will fall in line.