He should give you advice on layout and organization of your pages, and be able to explain how your page will be pleasing to customers. He should be able to tell you the important items to include on your site that draw customers into a business relationship with you. Don't buy promises of what will happen tomorrow. Technology on the Web is moving rapidly in many directions. Your Web Designer should know what your audience needs today.
Simple sites reach all people, while technological tricks limit market share.
Look for proven experience. A good Web Designer combines excellent graphic skills, programming, content development, and knowledge of how the Web works. Make sure you get this combination and don't settle for less. The look of the page, making the text easy to read and navigate around, and a strong focus on your business' bottom line are the most important requirements of any Web site. You need much more than a techie.