Don't Crowd The Screen - A very important rule to remember when designing a web site is to leave a bit of space. Leave margins, use short paragraphs and don't have long web page.
Stay up to date - Keep the content on your site current. Most popular web sites are updated daily, You got to keep them interested. If you own a news site or a site that has news you need to keep it up with the latest news because no one wants to hear about one or two days ago news!
Java Clock - Why have a clock on your site? If a visitor needs to know what time it is they can look at the clock in their house or the one on their computer. Also browsers often crash on web pages using Java.
Big Graphics - It will slow your web page down and most surfers leave after ten seconds, causing you to lose customers.
Advertisement - Visitors hate any kind of advertisement, no more than 1 or 2 banners. Popup windows are also other way of advertisement, Which use to work really well, so well that every webmaster started using them and the visitors refused to look at them any more because they got so burnt out of seeing them!
I can't read the text - Not only black text on a dark background, but light color text on white backgrounds and tiny text is a pain for people that can't see real good.
