Social proof is powerful, but most testimonials are useless because they're generic. 'Amazing, highly recommend!' could be about anything and convinces nobody. The ones that move people are specific about a real result and a real doubt.
Collect the useful kind
Ask buyers what they were worried about before buying, and what changed after. 'I thought it'd be too advanced, but I set it up in ten minutes' does more than a hundred five-star adjectives, because it answers the exact objection your next buyer is having.
Show a face and a name
A real name, a photo, a link — anything that says a genuine person stands behind the words. Anonymous praise reads as invented, even when it isn't.