Given that your blog has great content, it should also be presented in an organized way. Link within, smart layer are some must have widgets for the same.
Broken links irritate visitors and can badly affect your ranking. Check and repair all such links on your blog.
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.