So, what is Instafreebie?
Instafreebie (here) is a site that gives e-books away free to anyone who wants them. That sounds nice for readers, but not great for authors . . . except that the giveaway comes with a sweet little wrinkle.
Because, in order to collect their free ebook, readers have to give the author their email address.
Here, for example, is what an Instafreebie giveaway page looks like. There’s a book cover. A “come and get it” headline. And a really easy sign-up form.
So actually, Instafreebie isn’t really a way of giving away books – it’s a way to give away books in exchange for an email address.
And since presumably no one downloads a British-set crime novel (like my one above) unless they are actually interested in reading British-set crime novels, the email addresses that you can hope to collect are from the exact reader group you are seeking to target.
Expert tip: When you set up your giveaway page, you’ll be asked whether you want to force readers to sign up to your email list, or whether you’re OK making it optional. You’ll get more readers overall if you make it optional – but you’ll get fewer email addresses. So you DO want to require people to give you that email address. It’s what you’re here to do.
read more http://www.writersworkshop.co.uk/blog/how-does-instafreebie-work/