Visual design should be all about communication, but it often isn't. It is not about using the latest and most trendy font. It is not about adding bells and whistles to your site. It is about communicating and using visual design to help you do this.
In order to create hierarchy, you must first determine the hierarchy of your information. What is your site trying to accomplish? Selling something? Would the visitor want to buy something? If so, make your store the first read, and make purchasing goods easy and intuitive.
Once you know what you want to do, think about your site design as a series of "reads." Use visual devices to achieve hierarchy, such as: color, typography, scale, animation, sound, and interactivity.