There are lots of ways to increase conversions on your website. Using the right images, testing different buttons on calls to action, decreasing the number of pages in your shopping cart process. There are tools to help you do this, multivariate and split testing tools.
But one thing you can do before you even get to that point is proper keyword research. Conversions on your ecommerce site start way back here.
I have seen many people bid on (or worse yet, SEO for) a keyword because it has a lot of searches. Obviously we want traffic to our storefronts, because more traffic = more sales. Well, yes and no, more of the right kind of traffic = more sales.
A good way to do this is to take your internal site search and run some reports. There is a lot of information about how people view and search for your product. For example, you may sell "saunas". However, your internal search reports may show that most of your visitors search for "hot tubs".
Semantics right? However, if that makes the difference in how people view your product and influences them to buy, then it's obvious what word you should use in your marketing.
The research is worth it, in the long run it will pay off. Instead of trying to fit square pegs into round holes, you can spend your conversion efforts fitting round pegs into round holes.
Happy ecommercing! (Can I say that?)