How do you spread the word

about books you want to tell people about?
I had an e-mail from the local indie bookshop yesterday. It was one of those group e-mails they send out to everyone rather than a personal one. It informed me that an author would be at the shop to sign books on a certain day - for half an hour.
I have never heard of the author. I know nothing about the book. I won't be there anyway because I already know I will be elsewhere. It all seems a little odd to me - just half an hour?
I might check with one of the staff today. Is the book self-published? I suspect it is. Our local indie, unlike many shops, will give a tiny amount of shelf space to self-published books by local authors. As one of the staff told me, "A lot of the books are pretty awful but they usually sell a few copies because people know them."
I have bought just one self-published book from the shop. I didn't know the author but I knew the person who edited it. He recommended it as a gift for someone we both knew. I glanced at it before I gave it away. It was about a sailing, not something I am particularly interested in but they were. Because it had been edited by a professional the book was, if of limited interest, fine. Some of the others I have looked at have been dreadful. It puts me off the idea of even trying to self-publish something. I know that means I will almost certainly never be published but better that than putting my name to something which would make me and my family cringe.
And the publicity side? I have the impression the bookshop staff are not too interested in this author who only has half an hour to give to promoting his book. The bookshop staff do a pretty good job of author promotions. There is often an event with wine and cheese and a talk by the author or, if for children, a themed Saturday or holiday event. For a small bookshop which struggles to survive they do authors proud.
I know authors have to work at selling their books too and, if I "know" the author - even only virtually - and I like what I see I will encourage the shop to stock some of their work. They take my suggestions on board. Why not? It comes with a recommendation from someone who reads. The staff know I will tell people about the books I have recommended.
So, what's with this half-hour author? Who is he? Why just half an hour? How good is the book? I'll look at it and I will try to be open minded about it.
But, how do you spread the word? When Jen Campbell produced her first "Weird things customers say in bookshops" I showed one of the staff my copy - and they promptly ordered half a dozen. It's a perfect sort of gift book. It is the sort of thing they are often asked for. I suspect that her book about bookshops, "The Bookshop Book", will also be popular here. Would they have seen it without me waving a copy in front of them? Possibly not. There is a limit to the amount of information they can access. That's why I think it is important to tell them about things I know they might not know about. They will even ask if I know of anything.
Spreading the word about a book is done in all sorts of ways. Nicola Morgan and Linda Strachan, both people I know and respect, do a lot of work in schools. I suspect many other children's and YA writers do too. But, if you write books for adults, then you need to work in other ways.
I suspect half an hour in the local indie bookshop is not going to sell many - if any - copies. I might be wrong but I suspect it is much harder work than that.