The easiest way of getting people to do anything is: ask them to do it. Write in an engaging style, and then ask your blog’s readers for an opinion, their take on the story etc.
Another important things is your comment links. Is your comment link “No comments »”? Or is it “No Comments yet, your thoughts are welcome »”? Feel the difference? You can change this by opening your
index.phptemplate, search for
comments_popup_link()and changing the texts within that function.