What dangers should be avoided?

The use of Flash, Java are best avoided. This is mainly because the search engine spiders cannot read and index the Flash or Java files. If you want to use Flash best to keep it to a minimum and avoid using it in the menus if you want your website to be indexed and seen the search engines.

The use of Frames is another issue which has a problem with the spiders. They cannot see Frames so use of these should be with care.