On ColorThis is probably the least critical of my advice columns. But, color does bear some thinking about. You may really, really like masses of red and black (as I do), but it's not going to help you sell doll clothes, books on gardening, or stuffed animals.
One really important thing that has to do with color is the clarity of the text on the site. You want to make it very easy for your visitors to read your copy. Light text on a dark background in a normal size is extremely difficult to read for more than a couple of sentences.
Generally, any color you use should not detract or distract the visitor from the important information. If yours is not an entertainment site, then your visitor is not at your site to be entertained.
Keep the colors as much in tune with your message, product, or service as you can. The colors will unify your site and give it a look that should be consistent throughout the site.
One of the early web books I bought was Lynda Weinman's coloring web graphics. I loved that book, and it caused me to play around a great deal at the time. And, playing around is when you begin to discover things and really get a feel for what you are doing. If you want to treat yourself sometime, get a copy.