Testimonials work.

People who used your products verify your claims. It's a good idea to use testimonials from customers that were in a worse situation that the average customer. If even people in terrible circumstances could get the results, so can they!

A few tips:

• Testimonials must have full names, photos and preferably also links to their site or a job title
• Video testimonials are better than text
• Testimonials by known industry experts provide additional assurance