NOTE MSN has recently entered the search engine arena and has a slightly different take on these numbers. With them, the optimum number of words is between 330 and 430 total words or about two keywords for every 100 words on the page. Repeat the keyword or phrase 6 - 8 times on the page. Use the keyword once in the title , once in the meta tag keyword area, once in the meta tag description area, once in an ALT description, once in a heading also create a link on the page with the keyword in it. Title Keyword Density A keyword percentage factor is applied to the title as well.
Titles are arguably the single most important keyword weighted factor on a page.
The title is arguably the single most important area for effective keyword placement on a page so target the title well. Finding the right keywords and using them in a compact manner will return better results than using a plethora of words in the title. Some search engines penalize for using the same word excessively.