Subtle is the key word. Colors are a wonderful part of the Web, just try not to overdo it. Bright primary colors tend to tire the eye. Pastels and calm color combinations work better. Text should convey your meaning in as few words as possible.
Bad design leads to frustration on Web sites.
People expect your site to make logical sense and be almost intuitive to use. When it's not, they get frustrated and leave. But bad design isn't just layout. It's also poor use of color, text that is difficult to read, and links that don't work.