You are not immune. A stealth competitor can arise from nowhere and eat your lunch if you aren't adequately prepared. To begin with, it takes a strategy, an overall plan that encompasses the best elements of a successful e-com campaign. It may come as a shock to some, but e-commerce is not about having a marketing website, it's about transacting business over the Internet. And there are incredibly few barriers to entry for new competitors.
Strategy is everything.
Be sure to have one, and stick to it. Here are some basic aspects necessary to every e-commerce strategy. Managing this is known as customer relationship management, and it involves owning the total customer experience, helping customers to do their jobs and to serve their customers, eliminating barriers to transacting business by streamlining the process and packaging the whole experience as a highly personalized service. Focus on your customers. E-commerce is a vehicle for disintermediation.