It's easy to judge, easy to criticise. But take a pause. Remove your shoes, and wear the shoes of the other person. Try and think how the other person is thinking. Try and feel how the person is feeling. Only after you have done this, and you still feel you have a reason to judge, and criticise, then do so.
We all seek perfection in the other person, but not always in us. If you wish to bring perfection in the other person, become a good teacher. The best tool is love, the worst is fear. Use the tool of love. Through love, the training you give will be understood not only by the mind, but also by the heart. Great teachers don't only have great explanations for the mind, but they have great compassion for the heart. Be sensitive to the heart.
Put yourself in the other person's shoes.