In Wordpress there are actually a few different types of keywords and fortunately, plenty of places to put them. Most Wordpress users use the word tag which is really means keyword.

Here are the places you should be placing your keywords:

  1. Post tags - most people know this already.
  2. Within the posts content/text - most people know this already.
  3. In the meta tags - most people don't know this or don't think it is important - but it is important.

As far as the post tags are concerned, you should place your main, targeted keyword phrase as the first post tag followed by a few variations of that main keyword phrase. For example ...