You, as an author, are an expert communicator and believe everyone could benefit from reading your book. If you build an effective website, your sales can double. That's as good as writing another book. Unless you're defending yourself in a murder trial, your website is your most important writing project. They need an emotional experience.
Emotions motivate actions.
The emotion you want to create in your visitors is desire. The action you want them to take is pressing the order button. Things like wealth, love, knowledge, longevity, happiness, community, understanding, sex, peace, laughter, health, friendship, joy, beauty, fame, wisdom, excitement, nirvana, acceptance, purpose, or immortality. The purpose of your feature page is to convince the visitor that buying your book will help fill a desire. Every phrase can connect your book to a desire.