Listening to authority We all know it - people listen unquestioningly to authoritative figures. These people can tell you to do what most people can't and you will almost always do it without questioning it. This means that your site should have someone or some organization of recognized authority in that field saying something positive about your product or service. It doesn't have to be a famous person, just an authority. For example, a travel service can have a review by some magazines and a vitamin store can have some comments from some doctors.
Small agreements lead to bigger ones.
If someone came up to you and asked you for your agreement on some major issue, they are more likely to get a no from you than if they came up to you and led you on with a series of much smaller issues that you can easily agree on, building to the major issue. Getting people to agree to a major issue is a lot easier if you first give them related but smaller issues that they can automatically agree to. One way to use this in your business is to provide a free trial. It is easy to get someone to try something free. After that, it is much easier to get them to upgrade to a retail version.