Take a look at some leading blogs and evaluate how they use language, images, links, etc. Also note how they set a tone to communicate with their audiences. What can you learn from the blogger by seeing how the blog is composed? what can you learn about the blogger's (perceived) audience by looking at how the blog is composed?
You might start here: http://www.time.com/time/specials/packages/0,28757,2075431,00.html