When you write a blog post and try to optimize it for keywords, it’s great when you actually get ongoing traffic for those keywords.  These is also another factor with those words, what can happen is that you end up getting even more traffic for keywords that are similar to the ones you tried to rank for.

It’s important to consider these “related keywords” in your posts.  Don’t add keywords for the sake of it, but if Google thinks they are related to your main keyword targets, then consider adding them if they can add value to your content.

The best way of finding these keywords is by searching for something in Google, scrolling to the bottom of the page, and looking at the related keywords.