Series of articles - Create a series of articles on your blog if the subject you choose to talk about is an extensive one.
Always acknowledge a comment on your blog and respond to the commentator, preferably at his own blog. Its great to reciprocate the gesture.
Use technology - Social plugins and SEO tools are a great thing to market your blog or a blog post. If you do not know about it, then learn it. It helps you reach out your audience in a better way and also improves the ranking of your blog.