On the internet, so many people are concerned with actually getting traffic, usually via search engine optimization and / or pay per click advertising, that they kind of forget about actually converting the traffic. Admittedly, getting the traffic via SEO or PPC is the hard, and sometimes expensive part, but it would surely be a mistake to pay money on ads or SEO services, and then not maximize the potential of your landing pages.
The process of improving your conversion rates is known as conversion rate optimization, and it can result in more sales with the same amount of traffic.
A common way of improving your conversion rate is to use the free google website optimizer tool to conduct split and even multi-variate tests, organizing the different page elements into varous combinations in order to hit on the most effective and highest converting landing pages.
It may be an idea to hire a professional conversion rate expert to carry out this work, especially if you have a well established, highly ranking site that is already getting loads of traffic.