Optimizing your E-Commerce website to gain more traffic is a pretty simple.

Create content for category pages that tend to be heavy on images and links. "[W]rite descriptions or introductory copy for each category, to be displayed above or below the product listings," he recommends. "Zappos.com, for example, places a lengthy description (more like an article) at the bottom of category pages."
Rewrite product descriptions, especially those written by your suppliers. "Although category pages may be the focus for primary keywords," he notes, "product pages offer a wealth of longtail keyword opportunities. The challenge, of course, is that in many cases product pages use manufacturer-provided descriptions, which are duplicated across many other e-commerce websites."
Write expert reviews for the products and services you sell. "Those in-depth product reviews could include images, video, detailed product testing and analysis, and other value-added content that shoppers would find useful," he says.
Write buying guides that tell customers what to look for as they comparison-shop. "The guides are especially useful for products that may require specialized knowledge to understand," he explains. "[And they] can very easily be optimized for primary or secondary keywords because they typically have keyword-rich content."

Four Ways to Optimize Your E-Commerce Website : MarketingProfs Articles