Research has shown that the three most important factors influencing whether a customer will purchase from a consumer Web site are security and privacy, ease of navigation and quality of content. Make privacy and security information prevalent on your site and in the purchasing flow - including both detailed policy statements and third-party certifications. A logo from VeriSign, McAfee or TRUSTe, placed discreetly on the home and landing pages and prominently on check-out pages, can help alleviate a customer's concerns about credit and debit card transaction security, especially when shopping on e-commerce sites that lack national brand recognition.
In addition, find ways of giving your site a "real-world feel" - photos of your facilities or employees, for example - to convey the idea that there's a real company behind the Web site, not just someone in a garage.