Franklin had a pretty interesting way of improving his writing, which can be generalized. He would read articles that he liked, and then try to rewrite them from memory. That way he could compare what he wrote with the original - which creates a very clear feedback channel.
By comparing your choices with those of an experienced writer, you hone in on exactly where your mental model of writing needs improving. Depending on what you need to improve you can tweak Franklins model. You mention structural problems: to improve you could try to outline good blog posts from memory, and compare what your outline with the original. Where is your pacing off? How many examples do they use? Do you lose the thread? By comparing what you do to the original the nature of your problem will become much more clear, and you will have begun forming deeper, more detailed mental models of how to structure a blog post. You will start to notice classes of openings, different structural principles, etc.
You could approach headlines similarly. Ask a friend to email you sections of blog posts, and give them the best names you can think of. Then look at the original. Try to analyze why the original is better, and try to tease out how the author approaches headlines.