As with any text, you should have your audience in mind.
What questions does the reader have while reading your article? Why should I read this? What will I find in this article? Is this worth my while?
Interesting, how can I apply this to my situation? Why should I keep reading? How does this relate to what I already know about the topic?
If you are good at answering the question exactly when this question pops up in your readers head, you are writing a good blog post. Use pictures and headlines or quotes to break up the reading flow when you need the reader to think about what they just read.