The basic rules of effective testimonials

Once again, let's be practical. You're building a website for your brand hoping to convince people to buy your product. You've chosen great pictures, written carefully the tagline and the How it works section, done your pricing and contact information. The basics. 

You may think that customer testimonials could help build more trust. My guess is that it actually does. As long as you respect a few rules. And don't fall in the "it sounds fake" trap.

I've gathered a few good examples and the basic rules on a Slideshare.

Building the presentation, I've realized though that a few popular websites don't display customer quotes. It's not that they're already famous because a lot of famous companies use testimonials. My bet is that, sometimes, it can feel like you're overselling it. I'll let you be the judge of this.