First Person Reviews
Have you used a product or service and loved it so much you want to tell other people? I'm sure you have and you have probably convinced friends or family members to give it a try as well. The same kind of principles can work for Internet marketing as well. The difference with people you know is that they already trust you, but most visitors to your site are not going to know you from a hole in the wall. You have to build up trust by connecting with them emotionally.
Empathy
You really have to get in the mind of the visitor to write a good testimonial for the product you are reviewing. You have to figure out why a person would be interested in the product, what are they thinking, and how it will improve their situation? The more you can relate to what the visitor is going through the more they will believe you know about their situation. If you have walked a mile in their shoes and come out much improved, then you will be giving the visitor hope you know how to help improve their situation as well.
Features
What are the features of the product you are reviewing? How well do they relate to what the customer is looking for? You do have to talk up the product that you are promoting, but don't be too over the top. Remember you aren't a salesperson, but just a happy customer that wants the rest of the world to know about this miraculous cure for what was ailing you!
Address Fears
Why would they be reluctant to purchase the product? Are there any risks? If you are selling a product with a high purchase price, visitors are going to want to be extra sure it's going to solve their problem due to the high cost. Is the product promising something that seems unbelievable or too good to be true, customers are going to have a harder time trusting it will work. If it's a niche where the visitor has tried several different solutions and hasn't seen any results, you will have a harder time convincing them that you have the magic cure. Money back guarantees are almost a must these days. If you will give the customer their money back if they are unsatisfied, it's almost like saying to them "what do you have to lose anyway?"
Experience with the Problem
The easiest first person reviews are the ones that you write based on your own experience and believe in. If you have never hit a golf ball in your life it's going to be hard to connect with the frustration faced by someone who hits a huge slice and is shooting terrible scores on the course. If you are going to promote a product you don't have experience with using a first person testimonial, you need to either have it written by someone with experience or interview someone who would be interested in the product.