As an author, you might wonder why you'd need to build an email list. Short answer: email lists make things happen. But you need to engineer that by engaging, creating a platform for interaction, and building your tribe.
One of the most powerful things you can do to improve your book sales on Amazon is to choose the best category for your book. It is amazing what a few tweaks and changes can do for your book rankings! Within just a few days of optimizing one of my books, it hit #1 on Kindle for its category.