This article by Dan Frommer seems to have 2 main overarching ideas. Firstly, make sure that you blog is accurate and factual. If you post incorrect, redundant, or contradictory information, you lose credibility, and thus, lose readers. The second thing he mentions is to be interesting. He lists a couple of different methods, such as being opinionated, being a jerk only when it’s funny, be critical, and be original. People want to read something that not only informs them, but entertains them. He also mentions that the format of your posts should not remain ridged. It is ok to go outside your usual posting length, or even your posting content. He mentions such things as charts, data, images, and essays.
All in all, this article is a useful tool for those who want to get into blogging, as well as those already blogging.