If you have no formal design training, picking a color scheme is probably one of the weaknesses in your web development toolbox. Of course, sometimes you’re building a project where due to either time or budget constraints you are the designer.
One tool that eases this pain for me is Eric Meyer’s color blender.
It’s easy to use. You pick a startpoint and an endpoint, and are instantly shown the hex values and color samples for up to ten midpoints between the values you supplied.