Its not just good content that matters, presentation of post is very important too. Have attractive pictures, fonts etc to hook the readers.
Write something useful for your readers. Share a relevant piece of information, an event update or a hack that makes a task simpler
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.