Use Amazon Product Promotions to increase your sales
Promotions including Lightning Deals are a great way to sell units on Amazon at an increased velocity, ultimately leading to more reviews.
The goal is not to always be on promotion or providing deep discounts, but if you can sprinkle these in towards the beginning of your product lifecycle on Amazon, it is a great way to gain additional reviews and build relevancy so other customers can find you.
Sellers can also opt in for their products to be included in the Early Review Program. Amazon randomly selects customers who leave reviews and provides them with a small reward (such as a $1-$3 Amazon Gift Card) to thank them for sharing their unbiased review. There is no guarantee that this reviewer will provide a positive review, but it is still a great opportunity for sellers launching new products.