Blogging is more about you writing your experiences than what readers want to read. To get the right audience, follow your heart and write what you actually go through.
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.
Share your personal experiences on your blog occasionally. It makes your posts more real and helps your readers connect with you.