1.Music on load:- The music should not get automatically loaded when you visit a website. This can irritate and annoy the viewer at times as all visitors do not have the same taste in music.
2.Site designed for particular browser:- You should not design your website for any particular browser. Websites should be dynamic. If you limit your browser capabilities then you limit your visitor base.
3.Images must have ALT text:- ALT tag must be used for SEO purposes. Google,Yahoo loves ALT tags.
4.Automatic pop ups:- Automatic pop ups should not be used as it is associated with spam,it breaks the reader's concentration and people really don't pay much heed to it.
5.Bad site navigation:- Site navigation should always be good for the convenience of the client. Good content writing does not count if the navigation is not good.