While readers are great, more readers beget more word of mouth, and anyone who shares your work is a great help to you, not every avenue of promotion is equal. For example, while there are exceptions like the great Joanna Penn who gain a large following for their writing by building a writing-based blog, most often, other writers are not going to be an audience who becomes an avid fan base for your book (Let’s face it…writers are supportive of each other, but we’re busy focusing on our own books, too!). If you have a limited time to promote, head for spots where your target audience is (refer to number 1).
[Note from Joanna: I would second this point! I also wanted to note that I started this blog back in 2008 when I was only writing non-fiction and just wanted to document my self-publishing process. It has morphed into a completely different business and later I started writing fiction, but my site for that is at www.JFPenn.com where I DON’T talk about writing!]