Black Backgrounds with white text (Can strain peoples’ eyes.)
Browser Buttons or markers (“This page best viewed with Netscape, Mozilla etc.)
Animated Gifs (Avoid or at least minimize animated gifs) If you do use an animated gif, does it need to loop continuously? Tips: Set the last frame of the animation to pause for about 10 sec before it repeats, or set the animation to stop after three or four iterations.
Yellow “under construction” signs or animated gifs that serve as the universal disclaimer that a webpage is coming soon! Avoid, because all they really do is reveal the author’s lack of organization.
Counters (avoid) to endusers. The numbers are meaningless. For programmers they can start the counter at 4 million if they want to, to deceive you into thinking that the website is more popular than it is.
Avoid mystery downloads. If you provide a link to a downloadable file, be sure to indicate the size of the file and the file type.
Excessive use of different color. Use colors logically and sparingly with an awareness that every instance of a color can serve a unique and valuable purpose.
Excessive use of Font faces..Like color, the fonts that you use have a huge impact on your design. Font faces, should be used consistently with the primary goal of readability
Be careful with Splash Pages. Unless your website is designed as a purely visual experience and not a content resource, avoid using splash pages. they often create needless waiting periods. Don’t create a splash page that has maybe a logo and a line or two of text followed by click to enter.
Avoid Pop-up Windows unless the content within is best displayed that way.