Keyword Density
Keyword density has been a hot topic in years past when webmasters were trying to figure out how to get their pages to the top of the search engine results. Back in the 90's some people were worried about keyword density, prominence, variations, and all other kinds of non-sense. The "magic number" that you wanted to use for a benchmark seemed to fluctuate daily.
With the modern algorithms, density is something that can probably hurt you but not help you. You don't want to stuff your keyword into your content a bunch of times. If you are over-using the term you are targeting then you can harm your rankings or get the page de-indexed from the results completely.
With that being said, you don't want to ignore it completely. Here are some basics that I use for working my keywords into the content:
- Make sure the keyword appears once in the copy. This makes sense since if the article you are writing doesn't have the keyword included in it somewhere, then how can it even be relevant?
- Include the keyword in the title.
- The URL or permalink should include the keyword.
- The H1 tag should include the keyword.
Those four principles are really all I think you should worry about. When writing the copy for your blog or website you don't want to force the usage of a keyword with the notion that it is going to help you rank better. What it probably will do is turn off your visitors as they wonder if the person who wrote it is either a robot or on the lower end of the intelligence scale.
If you write quality content you are going to be better off in the long run. People will think higher of your site or brand, have a higher chance of subscribing to your RSS feed, newsletter, or interact with you on social networks, and they will refer others to your site as a source of expert opinions in the field. These benefits far outweigh trying to get as many people to your site as possible, only to have a higher percentage of them click their browser's back button after reading a few sentences of mindless drivel on your site.