How difficult is it to choose a nice color theme for your application or web site? This seemingly trivial task could take days of your time and you could still be far from being effective.
Though it seems easy to pick a bunch of nice colors and be done with it. It is far more complicated to choose colors that are effective and yet pleasing on the eyes. It is less of a science and more of an art, but fortunately there are best practices and thumb rules making it easier.
When I started meddling with the colors of our product, one things that struck me was that there is no universally accepted definition of what colors are nice and pleasing.
The Color Wheel offers a good guide to choosing the right contrast and matching saturation, but if you do choose colors that are not recommended by the wheel, you are cautioned against its usage but there is no obvious rule to stop you.
A more common approach is to look at nature or a picture atleast, to get a hang on what works well. There are creatures that want to present itself and some that want to hide. The monarch butterfly is a beautiful thing to watch, note the bright contrast of black on orange. Start with a couple of colors as your base colors and then use a color wheel to figure out what shades would work better.
ColorSchemer is a free and extremely useful online tool to suggest variations.