Number of Orders / Number of Sessions
The Conversion Rate is one of the key metrics when it comes to increasing sales on Amazon. Ideally, every visiting customer that has already found a product's listing page will convert to a buyer.
The main factors for a high conversion rate are:
Product Images: this Blog (click here) explains how to make the most out of product images.
Reviews
Price Promotions / Stroke Rates / Multiple Units Discounts: Giving customers the feeling they are "saving money" is one of the oldest but still the most effective "tricks" of selling more.
Information Texts (Bullet Points, Description)
Finally, this video (in German) will walk you through the process of optimizing your product's contents: