How to Sell Books

The buzz word for authors these days is 'discoverability.' After all, what is the point of  publishing your book if no one reads it? And how is anyone going to read your book if they don't know about it?
This may be less pressing with ebooks which don't incur all the production and distribution costs of physical books. Whatever form the books take, it must be possible to cut corners for writers on a tight budget, determined to see their work published. But publishing any book still costs money, time and effort. Someone has to do the work, and put in the hours.
Whatever their expenses, self-published authors don't want to be exploited. Yet a shocking 98% of self-published authors fail to even cover their costs. It seems that making money out of aspiring authors is a mega-industry these days. Someone is making money, and it's certainly not the authors.
Regardless of whether they are traditionally published or self-published, all authors want readers, whether because they provide them with an income, or for personal satisfaction. In order to survive, books ('products') need readers ('customers'). In this respect publishing is the same as any other business. Publisher and author enter into a symbiotic relationship. Successful books benefit everyone involved in their production: agent, publisher, production team, technical team, editor, proof readers, sales team, distributor, publicists, translators, bookseller, reader... it's a long list, right down to the modest author who kick starts the whole process.
What can authors do to find readers? That is the big question. Whether we like it or not, the stereotype of the author as remote and isolated in an ivory tower is largely defunct. Most authors nowadays accept that speaking at literary festivals and signing in Bookshops is part of the job.
But the best marketing comes from readers. Word of mouth is the most powerful marketing tool, and it's one that is impossible to control, except by writing books that readers want to read and recommend to their friends.
So the author's job is still to write the best book they can. Some things never change.