Long tail keywords always combine to create more traffic than the big ticket highly competitive ones, especially for newer domains. That is why creating a logical keyword focused site architecture with good navigation is the ticket for success on the web.
Using a certain keyword density when writing is old school seo in my opinion. I may do that for certain pages on a website but building a website that way will result in creating something that will not convert visitors into customers.
PAGE
Build web pages that are keyword focused. The page must have a purpose for your visitor. Target two, and at most, three keywords that are related to each other. The closing paragraph of the page should focus on closing the sale, or lead the visitor to read another page on the site.
The page name should be dash separated keywords that describe the content. Don't go crazy and create 10 word filenames.
Title
The title should be as short as possible, with the keyword(s) included at the beginning of the sentence (keyword prominence). Include the company name if appropriate. Separate using comma or dash.
Remember that the title is the first thing a prospective visitor will see in the search engine result page snippet, so a captivating title and snippet is critical.
Meta Description
Create the meta description tag to attract a click. Include keywords as close to the front as you can but never lose focus on attracting the click. Keep it short and sweet since snippets are cut at different points in the search engines. 150 characters and less will usually not get clipped. Google Webmaster Central has a nice write up about the meta description tag.
Meta Keywords
This tag doesn't do much. It doesn't hurt to include the two or three keywords your page is targeting, and some seo's include misspellings here, but don't stuff or spam.
