Grammar - Depending on the language you use, blogging just makes it imperative that you are reasonably good with your grammar skills and proficiency if not a master. Remember your audience is a mix of both; the ones who are experts and the ones who are not.
Create infographics for your blog to summarize the content and present it in a more interesting way.
Broken links irritate visitors and can badly affect your ranking. Check and repair all such links on your blog.