Being able to tell the others how they can improve is an ability that is needed in every social environment. Giving constructive criticism to a person can fasten the way they develop their skills or their behavior, which is why being able to give it properly is a skill that every leader or manager needs.
Be positive. You could have the best intentions when giving your criticism, but in this world, it’s easy to misunderstand intentions. You have to keep a positive tone as you want to sound like if you’re really trying to help, if you sound angry or disappointed the other person might feel attacked and your advice could be taken as offensive. Refrain from using phrases like “You’re so bad” or “Stop trying”, as no one likes to be attacked.
Start with some praise. Being criticized isn’t something most people are used to, and even if they’re used to it they probably don’t like it, so you must start with a little praise. Make a comment about what do you think the other person is doing right and then tell him where do you think he can improve, the transition must be natural and don’t focus too much on either comment. For example, you could say to a friend that is practicing a speech that his speech is really interesting but that he should speak louder so it can be heard better.
Focus on what you want to critic, not the person itself. If you want the other person to take your words as helpful suggestions instead of a personal attack you have to focus your criticism on the behavior and not the person. Instead of talking about the other person itself, talk about what you think they’re doing wrong, you don’t want them to feel like you’re being mean or hurtful, you want them to feel like you’re giving an honest opinion that will help them grow. For example, instead of saying “Your paintings are a bit ugly” say “I like the way you paint, you should take some lessons to become even better”.
Give proper suggestions. Just pointing out what the other person is doing isn’t enough, you have to tell them how you think they can improve or teach them what you know if you can. For example if your friend is trying to improve his guitar skills, you could ask him to lend you his guitar so you can teach him how to do what he wants to learn.
Finish with some words of encouragement. Remember that the point of constructive criticism is to help others improve and develop their skills, and even if you found the right words to point out their flaws the other person could end feeling disappointed about himself, that is why you have to finish your criticism with a positive comment or some motivational words, saying simple things like “I know you can do it” or “I believe in you” can make a big difference.