I have been working as an author (kindle fiction book) for several month. Then, I know a few tricks that's make me to get more sales. First, I publish my kindle book for $0.99. Second, run kdp promo for 2 days only. Third, STOP the promotion at the few hours before the end of promotion day. I recently using this method and I get 20-30 sales/book. Then, raise the price to $2.99. Your sales will decrease, but with 70% royalties, your income will be greater.