When starting an affiliate business, most people begin by creating a web site about one of their passions or hobbies. If you are thinking of starting one, think about who your audience is:
• What would they like to read about or learn?
• How old are they?
• What related hobbies might they have?
Then, ask yourself where those types of people "hang out" and find a way to make your presence known there. Join discussion groups related to your niche. Concentrate on providing useful information in the groups and on your own site and people will begin to recommend your site. Word of mouth recommendations are very powerful as you start an affiliate program--even after your established. Check your referrer statistics and see how people are finding out about your site. If someone has a link to you on their site, send them a quick thank you note! Those kinds of links provide wonderful free publicity and help your natural search engine rankings.