White balancing a flash or lighting to the color of ambient light makes a big difference and I have found it surprisingly frustrating to do. One has to guess the color temperature of artificial lights, which has become tricky with the variety of light bulbs. This is one area here cell phones are ahead of SLRs, since many of them have two LEDs matched to daylight and tungsten and try to automatically balance between them.

Finally a set of LED panels has an auto white balance feature, and one can press a button to automatically match ambient light.

Check out this fstopper post or the kickstarter.