Giving feedback is a sort of a delicate thing. It’s delicate because it’s very easy for people to take offense and therefore reject the feedback in its entirety.
E.g., how do you tell someone that he’s wrong about something? Telling the person that he’s wrong and that you’re right most likely won’t work. The other person would resist everything you say.
The reason is that admitting that you’re wrong would mean losing status. Essentially it’s an ego thing. My article “Maintaining your self-image” explains it further.
But giving feedback is necessary - how else would the other person improve. There has to be a way saying that he is not correct without making that other person feel immediately “butthurt” about it.
There is a well-known method of giving feedback in a structured way, and it’s called the “feedback sandwich.” It works like this: first you tell the person something positive about the work, then you talk about the problems and issues (the juicy part of the sandwich), and finally, you end the feedback with something positive again.
However, since it’s become so popular, many people see through it and in some business circles its become to be known as the “shit sandwich.”
A much better way to give feedback is not to give direct instructions but to let them reach a conclusion by themselves. It would be their decision, not yours and therefore they wouldn’t reject it. As soon as people feel they’re being instructed, they will resist you. It would be like swimming against the current. The person needs to see the errors himself.
Telling the person that they’re wrong would imply the opposite - that they’re incompetent and that would make them feel a lot of anxiety.
This can be done by e.g., telling the person “I’m sure you did everything you could. Let’s find a way to fix this.” This would not lower the other person’s status as it implies that they’re capable of fixing the issue by themselves.