If there's no magic formula for the perfect bargain each person will have his own psychological approach you should avoid two  Don't be too eager, and don't, on the other hand, assume everybody is out to cheat you.
You should not assume that every person intends to deceive you.
Mambo Italiano, leader of the Italian Mafia, told one of his henchman, Joe, to get into a fight with Siciliano, the Italian Mafia's worst enemy.