Never mess your blog with too much of Adsense ads. It gives a confusing look to the blog.
Acknowledge and appreciate your readers, especially regular readers by replying to comments and visiting their blogs.
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.