try to avoid using lots of animated gifs.
avoid tiled backgrounds.
keep the layout simple. Main page with welcome text, content separated into links, and good navigation. If necessary keep the main links on the page at all times, makes it easy to get around.
keep images at smaller file size, and avoid LARGE images, unless they open in a new blank window.

you have to have a pretty unique site on the web to get people to go back to it. its tough...think about what you would like to see when you go to a page and go from there.

Also, i would suggest using an ad-free site .. that will turn most people off right away.