The idea of keys to success is based on the need for focus. You can't focus efforts on a few priorities unless you limit the number of priorities. In practice, lists of more than three or four priorities are usually less effective. The more the priorities (beyond three or four), the less chance of implementation.
Virtually every Web plan has different keys to success. These are a few key factors that make the difference between success and failure. This depends on who you are and what services you offer. For one Web it might be great design (selling design and graphic services, for example), and another it might be ease of use and accessibility. For example, Yahoo! has concentrated for years on having a very fast site with standardized interface and limited graphics.
Think about the keys to success for your Web plan. This is a good topic for a discussion with your management team. What elements are most important? This discussion will help you focus on priorities and improve your business plan.