Colors that are too bright or harsh are hard to look at online and could potentially drive away customers. Bright yellows and "neon" shades come across as very "loud" on a monitor and viewers can feel "blinded" by the brightness of these types of colors.
Choose colors that blend well and are pleasing to look at together. Colors in the same family usually blend well together and are easy on the eyes. If you are using stock photos, choose ones that match the tones in the overall color scheme of your site for a uniform and polished look.
