If you publish books via Amazon KDP, you'll know about KDP Select. In return for publishing exclusively through Amazon you get to price your book to free for five days every quarter. The idea, obviously, is to encourage customers to try your work. Perhaps they'll like other things you've published and buy them. Perhaps they'll tell their friends, who will come along later and buy. Perhaps they'll all leave reviews.
In any case, it's worth experiemtning with. But what if you want a book to be permanently free? Now that isn't something I'd normally recommend. Giving stuff away for free isn't a great business model. But for books in a series, I think it does make sense. If you give the first one away, people will be tempted to download and try. If they like it enough, maybe some of them will come back and buy subsequent books. It seems like everyone wins: writer, reader and publisher. But, unfortunately, KDP Select doesn't let you do it.
Except, by dabbling in the dark arts of price matching, you can achieve it. I'd read about people doing this and thought I'd give it a go. It turns out to be extremely easy. I've price matched The Wrong Tom Jacks and it is free to download on both amazon.com and amazon.co.uk. It should be permanently free too. The approach is certainly effective. Tom Jacks has been hovering about the #1 spot in the free Kindle cyberpunk chart ever since. It's also been as high as #3000 in all free Kindle books, without me doing any publicity:
Now I just have to hope all the folks downloading it for free like it enough to want to pay for the other four episodes...
So, how do you achieve this? First, take your book out of Select. Then, when you're in the clear, publish your book to other ebook retailers (e.g. via Smashwords), specifying a price of free. Finally, once your book is appearing on the other book stores for free, tell Amazon about it. There's a link to do that on each book's page:
That's it. Hopefully, within a few days, Amazon will adjust their price to match and your book will be set to free. It might be a good idea to ask a few friends to report the zero price, too. Quite how Amazon's routines work is a mystery, but it can't do any harm.
One word of caution: I've heard of people getting their books stuck on a price of zero when they really didn't want it, so be careful what you price match. But if you're happy for a book to remain free (as I am with Tom Jacks), give it a go...