The Inner Game of Tennis talks about how you need to have awareness in order to improve. A teacher can tell you what you're doing wrong and what to do instead but you won't fix it until you're aware. He uses a drill where you see what you're doing in a mirror. This forces awareness on you.
So if you're trying to improve yourself, find out how to direct your awareness toward problem spots.
How can you apply this to helping other people? If you tell someone what's wrong with them you're more liable to destroy a relationship rather than help them. Chris Voss' techniques work here. You force the other person to come to an understanding rather than telling them what the problem is. Empathic listening. If they feel heard, they're more likely to dig deeper into their thoughts.