One thing that will drive your customers away faster than anything else is poor customer service. This ranges from taking an eternity to answer your email to shipping delays. You need to respond quickly, especially when it comes to email. Nothing irks me more then having to dig through a site just to find an address to ask a question. The more ways you give people to communicate with you, the better.
Many companies fail online due to shoddy customer service.
Don't be one of them. By offering excellent service you'll stand out from the crowd and build better relationships with your clients. Identify your company and your products on the home page. Also, make sure you describe the benefits of your service or product right away. Tell them and tell them fast, or risk losing them.