No matter how nice the composition, flow, and lines of my design are, if I am not copying directly from nature, I have a very difficult time picking a decent color scheme. It either looks too drab, or too garish.

Is there a good resource that will help me to choose a color scheme that has 2 or 3 colors, and the colors do not clash?

I'm not looking for specific colors or color schemes. What I need is a resource that will help me choose a color (or colors) that go nicely with, or provide a good accent to, whatever main color I am working with on the design.