Build it and they might come.
Build trust and they might stay.
Make it usable and credible and they may tell their friends.
The first step in building a successful website is to provide something people want or need—like a product, information or service.
After that, it better be easy to use. Now you may start to get users telling their friends, tweeting about your website and posting it to Facebook.
See on www.measuringusability.com