Take notice of any customer feedback that you receive. Your customers will tell you how easy your website is to navigate and how easy or difficult it is to find the information that they are looking for. If your website is an eCommerce shop, ensure that the category structure is intuitive. Ask your customers by sending an email after they have purchased to ask them what they thought of different aspects of your site. By collecting information in this way you will gradually improve your website and gain more sales.
A review system on each product page will give you invaluable information as to how accurate your product description is. Customer reviews should be taken notice of and not just thought of as valuable content that will bring the search engines and raise the ranking of your page. If a customer review says that a product description could have better, it might be worth checking if of this item has been returned to your store as this may have been because the item description was not as full or accurate as it might have been.
Its always worth asking as many people as possible to review your website structure and layout. As wide a demographic as possible as well. An older person will review the general layout of your website much differently to that of a younger person. To gain more sales in your online shop, your website needs to appeal to as wide an audience as possible.