Adjusting the white balance of an image for creative purposes is something that every photographer should consider to give everyday images a different feel. Sometimes, the camera's auto white balance settings won't do an image justice, so the way forward is to manually adjust the white balance.
White balance is all about the temperature of the light under which you're photographing. The standard household lighting in your house will either have a yellow or green colour cast, depending on whether the lighting is fluorescent or incandescent. There will be settings on your camera for adjusting the white balance to either of these.
Other white balance settings you're likely to come across are daylight, cloudy and sunny, which will make the image look natural in each of the relevant situations. But, these settings can also be used to get creative with images under different lighting situations, too.
Let's take the example of a sunset image for this scenario. Using the sunny white balance setting will give you a pretty natural looking image, but using the other settings could give you a more original take on the scene. Using the cloudy or shady setting for example will emphasise the warmer colours in the sunset, the reds, oranges and yellows, to give you a vibrant, more colourful image.
Using what would here be classed as the wrong white balance setting, such as fluorescent or incandescent can also produce some interesting effects. The fluorescent setting will give the image a purple/pink hue and the incandescent will give a much, cooler, bluer rendition of the image.
The best thing to do is experiment with the white balance for each image until you find the one that works best for the look you're trying to achieve. If you can't find one that looks right, why not create your own using the white balance preset tool. How to do this on your specific Nikon camera can be found in your user manual.