I've helped a lot of folks who had a blueish or yellowish cast to all of their images simply by making this simple adjustment — moving their white balance from tungsten, sunny or cloudy to auto. It's a quick fix that will really affect the color of your images.
What's going on with white balance?
It's your camera's sensor trying to adjust for different temperatures of light. For example a room with lamps in it has a very different color temperature than being outdoors under a shady tree — When your camera is set to auto white balance, it will adjust accordingly, to suit the current lighting temperature. Got more than one light source in a single image (for example lights on in a room and natural day light coming through the window)? No problem, auto will still come out way better than trying to decide between tungsten (lightbulb light) and daylight. In this instance, auto really is your friend.
Bethany Nauert, a professional photographer and one of our top tour contributor's at Apartment Therapy had this to say about white balance:
"There is a common misunderstanding about indoor lighting; yes it's pretty to the eye . . . But it is the enemy of white balance. Remember if you're going to shoot a room with lovely warm lights all along the bed side table . . . that warm light will distort the color of the walls, bedspread and pretty much anything around it."
Leela the Photo Magician
Image: Creative Commons by Bruno Girin