Flashy designs and elaborate interfaces have their place, but above all else a website must be usable. Businesses need to design websites that are easy to navigate or they risk losing customers due to frustration.
One of the best ways to ensure that users can navigate your site without difficulty is through usability testing. All it takes is a handful of potential users to perform a series of tasks on your website, such as finding the home page, making a purchase or signing up for your newsletter. (Via Marketing Zeus)