When you are marketing anything, you need to use some form of testimonial to help potential customers gain more trust in your offer. Any sales copy will be hindered by the lack of testimonials which is why people do limited releases for their products so they can have some ready for launch time. The thing you need to do is take action with this, and we can supply the "what to do" part in a few moments.
Sure, testimonials can be great, but the case study can really nail things if it is a high quality job done. As you can easily imagine, any time you do a study on anything it implies work and good details to show your point. There are many types of case studies, and this one could even be one that involves your customers. Yes, you may get those who could offer something less than positive, but that is quite all right because all people realize there really is no perfect product. If you look around, you'll see many major corporations publishing case studies from their customers, which they know will help them convince their prospects better and get more sales. So if you have a product or a service that is known to help your customers in a big way, then have a talk with them and see if you could get a few good case studies going.
Video is still hot with no apparent signs of letting up, and so let's turn our attention to what can be done in this area. It is common knowledge with experienced marketers that video testimonials blow all the rest out of the water. Even if you do take advantage of video, you must still have good sales copy, a good product and a good and solid offer. As for the credibility factor, just do not use someone who is not telling the truth. The really down side to this is it can prove near impossible to get a total stranger to shoot a video and send it to you.
Take a look at possible places on your site that would be great spots for a testimonial, and that can be used to positive effect if you put some thought into it. This approach will be very useful if you have an authority site because there are so many opportunities for using them, and if you have multiple products then you will have a lot more testimonials.
There is a lot you can do that will work to effectively provide testimonials for your business, and you simply need to put them to practice.