Because, let's be real, your clients are not going to take your "I'll just wing it" approach to negotiation any more. It's time to up your game.
Also known as "The Art of Not Getting Played", this technique involves carefully studying the other party's body language, tone, and facial hair to anticipate their every move.
Don't forget to Psychologically manipulate your opponent, but not so much that it's obvious.
Disclaimer: Results not guaranteed. Or are they?