Always keep in mind that when blogging you are writing for an online audience. This is different from the curl-up-with-a-good-book audience. Your online audience is going to have a shorter attention span as they are looking for entertainment to pass a few minutes rather than a few hours.
Your blog will eventually attract regular readers. But you have to create posts that could appeal to the casual passerby. Therefore, it is important that your blog is skim friendly. A reader should be able to get the gist of your post after one quick read-through.
This means that the post should have one main point, contains smaller paragraphs and you should italicize or boldface the really important points. Your post should also jump straight into your topic; avoid long, flowery introductions. If your topic is interesting, people will want to keep reading.