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.
Write guest blogs for others and have guest bloggers on your blog to widen your audience.
Write something useful for your readers. Share a relevant piece of information, an event update or a hack that makes a task simpler