You wouldn’t water down your cocktail would you? Well then stop diluting the strength of your keywords!
When I say diluting your keywords I am referring to tactics like keyword stuffing. For instance, a title tag that includes five of your keywords in it will dilute the strength of any one of those keywords. Instead, use only your top two keywords in there and they should be similar terms. The same thing goes for your meta keywords and description tags. Basically one would create lists of around 5-7 keywords to target on any given page. But targeting any more than this dilutes the strength of any one of those keywords and may also confuse the search engines depending on how closely related those keywords are.
Diluting your keyword strength is similar to the idea that if you have too many links going out of any given page, that you dilute the flow of PageRank to those links within your site. So if you were to target 3 keywords in your title tag you would be diluting the weight search engines might attribute to the words in your title tag. Using only two of the keywords in the title tag gives more strength to those two terms. And with competition on the Web growing at an exponential rate you need all of the strength you can get. This idea is not as important when talking about the meta keywords and description, but it is still important to remember.
Any professional SEO consultant will know these things so make sure that you are not using too many keywords on your pages, that may be holding you back from ranking. And when you are writing your content, or determining which keywords you will be assigning to which pages, always remember to not get greedy and use too many keywords on each page.