And the best way to do that is with data. Real statistics that prove where your website does well, and where it's frustrating and scaring away customers.
Even the best designers in the world can't design something that people love without finding out what people love. That's a given. And even if you do all the research upfront, there's no guarantee the market will be in the same place 6 months or a year later. Continuous usability testing is a sure-fire way to guarantee your website stays up-to-date and meets users needs. It also provides valuable insights into different directions your business could take.
Your customers need to FEEL connected to your website to buy things from you.
If you're trying to beat your competition, enhance how your users feel about your company, products and brand as a whole. You can't force them to press that 'Buy' button, but you can make them trust you, with a solid and intuitive website.
User Experience is a vast science of vital interactions between a website and users. UX isn't fluff you add onto a pretty website. It's the core foundation and psychological difference between an average and outstanding product. For more on usability, read some articles by the father of UX, Don Norman.