Long pages without white space or relevant graphics. Unless the page is meant to be printed instead of read on the screen. Backgrounds that result in unreadable text or are distracting. Avoid dark colors combined with dark text fonts or distracting images that overshadow the text. To begin, stay with a white background.
Broken links are a sign of an outdated site or one with a low quality control.
Overuse of fonts, colors, and animations. Did you know the average person's Internet attention span lasts for about seven seconds. Make sure your pages load quickly or at least warn users about pages requiring longer download time.