Best practices for hyperlinking in help?

[Leonard C. Porrello]

In my on-line help, I have been using a hyperlinking convention
according to which I hyperlink only the first instance of a phrase. For
example, if "metadata catalog" appears several times in a help page, I
hyperlink (to the glossary) only the first instance of  "metadata
catalog". I've been wondering, however, if this is best. Because users
often read help pages topically (not from top to bottom), I am concerned
that they'll likely not notice a hyperlink to a glossary entry if there
is only one hyperlink at the top of a page. On the other hand, if I
hyperlink every instance of a phrase, the text often looks too cluttered
with links. I have a solution in mind, but I'd be grateful for any ideas
about best practices. 

Leonard C. Porrello