Based on my experience a blog is not the place to sell books. It remains a fantastic way to learn discipline since a blog only exists if you post regularly. It can work as a publishing tool if your niche is extraordinary unusual, but we are so many bloggers that it can be as challenging to be noticed as a blogger as it is to get an editor or agent for a manuscript. However I still blog for the unique exchange opportunities and maybe one day this readership will boost my sales. Best to you and looking forward to read more on the topic.