How to keep emotions out of criticism

Hey guys. So this is something I have been wanting to work on and understand. How can I give constructive criticism and keep my emotions out of it? 

I got this idea from a book I listened to on Audible. It's called Unreasonable Hospitality by Will Guidara, and one of its chapters spoke about how a restaurant owner would address issues in his team. He told a story about a server who would come to work with a wrinkled shirt. In an attempt to be liked by everyone and avoid confrontation you, as a manager, would let the first instance slide, then you let it slide the next day, then the next, and then again. By day 20 you begin to take it personally, you start to believe that this person does not care about his work and his image when the reality is he did not iron his shirt because no one told him to. That resentment festers, by the time you address the issue it will go bad. Instead what you should have done is addressed it day one and say, “Hey, good to see you this morning. That shirt is looking a little rough, why don’t you head upstairs and give it a once over with the iron before we start our team meeting"

My brother would often get me upset and I would try to correct him when he did something wrong. But it hasn’t shown much productive results. Using this book I listened to and hearing other’s advice on how to critique, I want to break it down for us.

• First, you compliment and say what you like, then you say what you don’t like and lastly, you say how they can improve. Try saying “I appreciate your effort” or “Have you considered”.
• Praise in public, criticise in private, praise with emotion, criticise without emotion. Make expectations clear and make corrections quick and in private.
• Be thoughtful with praise as well as criticism. Put effort into how you reward, the more personal you can make it, the better.
• We tend to let minor infractions slide for the sake of being liked. This is a mistake. This can emotionally charge over you time. When you finally have the conversation it will turn messy.
• Correcting someone in front of people may make them resentful. And it will be something they never forget. Often times they would be so embarrassed they will be unable to digest what you are trying to tell them. So correct them in private.
• Praise more than you criticise or your team may become unmotivated. Tell them more about what they did well than what they can do better. And if you can't find more compliments than criticism, that’s a failure in leadership. Either you did not coach them well or you tried and it's not working, which means they shouldn’t be on the team.
• Be stable in your emotions. Do not take life’s issues out on the person you are trying to correct. This is the ideal but everyone is human, so when it does happen apologise. Not for the criticism but how you delivered it.

If you want to learn more about this topic and others I highly recommend his book. You can purchase it on Amazon using this link: Unreasonable Hospitality