Hi Downsouth,
Just took this out of the Econsultancy SEO best practice guide. Hope it helps.
1. For pages optimised for a specific phrase aim for a density of 5-10%, but dont fixate on this, using natural language blending synonyms and different sequence of keywords is equally important. Of course, generating quality external links is more important still.
2. Penalty warning: Avoid a possible penalty if density too high for particular phrases, i.e. >> 10%.
3. Use synonyms as well as identical keyphrases. Googles related searches47 feature which it uses for a limited number of terms may helpful here
4. Vary use of keywords in target keyphrases; they dont have to be in a consecutive phrase, e.g. for phrase‗uk insurance, variants could be ‗insurance for UK drivers, ‗UK drivers insurance, etc. The challenge is to
use these naturally within the copy.
Things to watch for:
1) Reviewers believed that density is no longer a significant factor within the Google algorithm to counter previous ‗over-optimization approaches. Instead, inbound links with an appropriate context for the
destination page are more important.
2) Use this tool which shows the frequency and density of different keyphrases: Abakus Internet Marketing has some tools available which might be helpful for this (German site).
3) Other on-page optimization factors such as formatting, and page connectivity factors such as link popularity and PageRank of a page and its authority
And position of keywords?
1. Include target keyphrases near the top of the body copy of the document.
2. Structure the code of documents forming the page templates of sites so that the body copy appears in the document before the main navigation (if practical).
3. Repeat the phrase regularly throughout document and include at end of document, particularly in hyperlinks to sections to find out more.