Quantity is not only good use of keywords but also the quality of how you use them in your website. Keywords used in the page title, Url, headings and first few paragraphs are considered as treasure mines by search engines. They are considered valueable compared to the other keywords that you place in the buttom position of the article.
Using the right keywords placed in the right places will nitro boost your success when compared to the competition who has the same keyword density but doesnot have the keyword in the right vital positions like domain name, first paragraph or title. Google, Yahoo!, Bing and other search engines will recognize your website as more relevant and more important. Here are some spot where they count most:
File Names and Urls
Your domain name serves as the signboard of your business. When you have a website about cell phones then you might have to put cell phone or mobile phone in your domain name. To trim it down bit, if you have a mobile repairing service then it might be best if you incorporate this in your domain and make it sound like mobile0phone-repair.biz or.com.
Putting as much major keywords in your Url may help your ranking but you also have to think of how people will recall your website. Keyword greediness will not be very helpful if you are thinking of a domain name. As a measure, more than three words in the domain name sound a bit much.
There are available online tools which can help you think of domain names that are keyword rich. These tools will be able to help you out in case the names that you thought of are already taken.
Search engines will also find websites relevant if you use keywords with your directory and file name.
Page Titles
Page titles are great spot to place keywords on a webpage. It may not be mandatory to fill up for the sake of SEO. Unlike the URLs, page title may be as wordy as you want so you have the chance to inject some important keywords.
Headings
Heading serves a lot more purpose aside from making your web page friendly to the reader's eye. From an SEO perpective, headings which will divide the paragraph are very important especially if they contain valueable keywords.
There is no written guidelines as to how many words a heading must have but common sense dictates that too long a heading will mean poor readability of the page. You need to consider less than 8 words at max for good heading. You can also vary the heading's font and color.