With millions of Web sites, chances are your long-term customers won't come from the ranks of the curious Web surfer, but rather from your continuing efforts to promote your site. Create an emailing list. Only send email when you have something valuable to offer or say. Keep in mind, many people skim email messages. Purchase email lists.
Many vendors sell email lists, targeting a variety of audiences.
Then, based on the response rate, determine if the cost of acquiring that customer was worth the investment. These new customers can be added to your database for future communication. People should never receive your email in an unsolicited fashion. Make sure they really want to hear from you. Create a regular e-newsletter.