Picked up this book by Dale Carnegie, which was first published in 1936, and continued to be a top notch book on self improvement.
It might seems obvious, but most of us are doing it wrong.
Avoid argument.
You can’t win an argument. You can’t because if you lose it, you lose it; and if you win it, you lose it.
The only way to get the best out of an argument is to avoid it.
Never Say "You're Wrong".
It's better to say "Well, now, look. I thought otherwise, but I may be wrong. I frequently am. And if I am wrong, I want to be put right. Let's examine the facts..."
Diplomatic, but it shows respect, and a win-win.
Galileo said,
You cannot teach a man anything; you can only help him to find it within himself.
Socrates said,
One thing only I know, and that is that I know nothing.