In general, there are a few things to watch out for.
Normally, search indices will use the first few lines of text from
a document as a short description to display in a search result. If
for some reason you want a different text, use the
element as follows:
<META NAME="description" CONTENT="Your description here.">
The description cannot contain HTML markup, and should be less than
1024 characters in length.
In the same way, you can add extra keywords:
<META NAME="keywords" CONTENT="Keyword, keyword, keyword.">
These keywords are used next to the ones found in your document. If
you overuse a keyword (some engines use an upper limit of 7
occurrencies) the entire list will be ignored.
That does not mean the site has to be boring and devoid of graphics. On the contrary - just make sure they don't distract from the main purpose of the site. Plug-ins, background music and animations have a purpose, but unless they are essential to the site's message, do not focus the reader's attention to them. And never exclude a reader just because he doesn't have a plug-in for something you offer (don't bother with the mechanics).
Also, if there is more information on some subject, put it on the site, don't just add a 1-800 phone number with the text "Call us for more information."
Imagemaps also often take a long time to load. For this reason, avoid them on the main index pages. An index should load fast so it can be used immediately.
Similarly, if a document uses plug-ins, you can add a link to download the viewer, but don't distract the reader from the actual contents of the document.
It is usually not necessary to include information about the links included in documents. Only add information if the resource is in some unusual format, or is very large. For example, if the site offers a 1.44 megabytes AVI movie, a text like "(AVI, 1.44MB)" after the link could be used to indicate this.