Tips for using white balance
You can rely on AWB much of the time. This is particularly true if you are using a strong external light source (such as a powerful flashgun), as the neutral light emitted by this will usually cancel out any color casts.
Some subjects can cause a problem for AWB, though – in particular, photos that have a natural abundance of warmth or coolness. The camera can misinterpret these subjects as casting a color cast over an image, which the AWB will then try to adjust accordingly. So, for instance, with a subject that has an overabundance of warmth, the camera will cast a blueish tinge over the image in an attempt to balance this out. Of course, all this does is leave your camera with a funny color cast!
Another confusing thing for AWB in cameras is mixed lighting (such as where an image has a mixture of ambient and artificial lighting). In general, it’s best to manually set the white balance for the ambient lighting, which will give everything lit by ambient lighting a warm tone. Warm tones tend to be more attractive to the eye than the very cold and sterile cool tones.
Understanding how color temperatures and white balance modes is important. Everything in photography is tied to light so it’s crucial to understand how every aspect of it works.
More about White balance modes.