I've been into photography for more than a year now and I've learned a lot of things through many of my mistakes. One of the common mistakes by most amateur photographers is setting the wrong white balance on their camera.
One way to find out if your shooting photos with a wrong white balance is that areas which are supposed to be white are usually the same color as the available lighting. Although auto white balance often works, their are some instances where the available light are mixed or beyond the capabilities of your cameras auto white balance.
The easiest way to set your white balance setting to your current environment is to manually set it. Most DSLR have the ability to set the white balance manually, all you need to do is to press the button which in your DSLR to set the white balance manually and shoot it at any white or gray object. I usually use a piece of tissue or a white hanky to do this.
If ever you've taken some photos which has a yellowish or blueish tone in it, there are still ways to save these photos. If the color isn't that off you could always set it to auto level in Photoshop. If the photos have a deep yellow or blue tone in it, there are still ways to fix this problem. My current work flow in fixing this problem is to adjust the color balance first in photoshop then adjust the hue/saturation setting of each color. Depending on which color you want to tone down. One method is to increase the lightness of the color you want to tone down or decrease the saturation.
I hope these tips will help you in shooting your photos.