A couple of months back, I wrote what was supposed to be the start of a three-part blog series on book marketing. It was intended as a sort of all-encompassing thing, covering the ins and outs of mailing lists, back matter, social media and blogging. I’ve had a few people ask me when the follow-up is due, so this is something of a response.

I hold my hands up: I couldn’t write a complete guide to book marketing. Why not? Because book marketing is constantly evolving. What might have worked yes...