Keep Important Design and Content Elements Above the Fold
It is important to remember that visitors to your Website are using a variety of screen sizes to display Web pages. Sites are often designed with the developer’s screen as the default. Review your Web stats and undertstand the various screen sizes used by site visitors.
Content or design elements that are below the fold, or below the screen, get less attention and are often missed. This is seen on a regular basis in user testing and is more important then ever due to the growth of mobile technologies and the huge variety of screen sizes.