Get to the point and provide a wealth of information about your product or service. But, ensure that you leave a little to the imagination. And, on that note, make sure your contact information is readily available on your site. There is nothing worse than peaking your site visitor's interest and then making them search for a means to contact you. Believe me, many people will simply give up if they can't find what they are looking for and go on to another site in hopes of an easier route.
Navigation is another key element.
Getting around your site should be straightforward and painless for your visitors. Provide links from each page to all your key pages. Some sites can become quite large, so links from every page to every page would make the site quite crowded and monotonous. But, make sure you don't leave your visitor at a dead end. Limit the use of unnecessary graphics and pictures.