This article came to me via one of my fellow Inkslingers, thank you Gale. I found it a great resource for writers just starting a blog or even those looking to refresh their current blog.
I have heard many writers ask, “Where do I start with a blog?” The simple answer is, you start with the content. What do you want to communicate to your readers? You can try a scatter-shot approach at first and see what generates the most activity but you run the risk of diluting your message. Ideally when someone thinks of your blog one thought should come to mind. Focus will ground your blog and I believe lend it an air of credibility.
To help you along your way, Pro Blogger has a great resource: How to Write Great Blog Content. Think of this as a aggregate of articles dealing with various topics like, how long should your posts be, how to make your blog scan-able, how often should you post and so on. The examples and lessons here could take you years to learn on your own. I have had this blog for two years now and I took away a few tips and had confirmation of things that I have observed. I recommend you give the link a click.