If your camera has the live view function and has a dedicated ISO button, you can preview your white balance setting.
Even though I understand the theory behind how the white balance setting affects the image, I have yet to master anticipating the white balance setting to use. I have my white balance set to Auto almost all the time. When the camera is unable to give the correct white balance setting, I would have to try the different white balance modes in an attempt to get the white balance closest to my desired outcome.
When I used my D40, I had to shoot at each white balance mode and then view the resulting images. With my D90, I can use the live view function to preview the outcome I would get with each white balance setting.
- Turn on live view.
- Scroll through the different white balance modes. Your LCD screen will show how the mode you chose affects the colour cast.
- Shoot at the white balance that gives the result closest to the result you want!
This can help you to better understand what each white balance mode does to your picture.
Of course, you can always shoot in RAW and correct the white balance during post processing. I prefer to get it right in the camera whenever I can.