Always let the picture do the talking! As a picture speaks a 1000 words.
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.
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.