Any advice / hack / trick that you learned from any book and have applied in your life and benefitted from it.
It's a self help book on how to have better conversations. The main point I took away was that its usually pretty cool to acknowledge that you had heard what the other person had said, before you make your response.
So, when I have a conversation, I make sure to restate what the other person is trying to communicate to me as accurately as possible, to make sure that I understood the comment and that my interlocutor can see that I have heard them. Saved my relationship with my brother, improved my relationships with my friends, helped me making many more friends - 10/10 recommend