Optimizing an ecommerce website is not dissimilar to optimizing any other kind of website - you need to make sure your meta data is placed correctly, your copy contains your keywords, and all the other components that any SEO company knows are necessary for good rankings. 

That said, ecommerce site typically contain more pages than other types of sites - for instance, our SEO firm just optimized a site that has over 1800 pages of products!  Clearly, avoiding duplicate content and ensuring that each page gets properly crawled and indexed is essential, as is making

The real power of ecommerce SEO lies in the long tail - search users are becoming more sophisticated every day, and searching for the exact products they are looking for as opposed to something more general.  For instance, they are searching for “blue suede shoes in a size 8″ as opposed to “blue shoes”, and of course the more specific the search term, the closer the consumer is to actually making the purchase.

Being on page #1 for thousands of long tail keywords is what makes an ecommerce site successful.  The success of sites like Amazon and Ebay show the value of the long tail - they do have best-sellers, but the vast majority of items sold are only popular with narrow niche audiences.

Just because the long tail keywords have a lower search volume doesn’t mean they are not worthwhile; not only do they drive traffic that is closer to the actual purchase, they are relatively uncompetitive, making ranking for them easy.  Optimizing for the long tail shouldn’t be an option for ecommerce, it should be a must.