Put advertisement but make sure that your blog visitor doesn't get irritated when ads pop up one after another like a flood.
Make sure you are interacting with your readers! If you are not doing so, your are not blogging.
Avoid using SMS abbreviations in blog post and at least run the post through a spell-check in MS-Word before publishing. If the bloggers cannot take the time out to write proper English, why would the readers bother reading through that cryptic puzzle?