Reviews are an inevitable and unavoidable cost of getting business online. Rather than fight it, just work with it.
Most happy clients will not leave a review- so you have to ask them to. Even then only a fairly small percentage will do it.
Most unhappy clients will not leave a review either, so you don't need to spend too much time worrying about it. The two times you will get a negative review are (1) the difficult person who is hard to please and often leaves negative reviews, and (2) the person who feels that you treated them so poorly that you should be punished.
Person 1 is a fact of life, so you just have to make the best of it. Respond in a calm and reasonable way to the review. This shows future potential clients that your reviews are not fake and that you care about your reputation. Studies have shown that people are more likely to trust a body of reviews when 1 or 2 are negative.
Person 2 can mostly be avoided by handling difficult clients, difficult projects, and mistakes in a mature and humble way. We all screw up, but when people feel they have to punish you it's because you were rude, dishonest, etc. Be nice, willing to say sorry, and occasionally eat a little profit and you should be fine.