I've made many of them myself. DON'T Put up your Web pages and then ignore them. The Web is a living organism. It must be continually nurtured. Emphasize style over substance.
Information is the reason people go on the Web.
Give it to them. There's nothing wrong with being attractive, but you must have some good, solid substance. DON'T Put different menus on every page. You need to have a consistent, understandable navigation scheme. DON'T Use huge graphics without warning.