To influence people effectively you need to be both trusted and respected. You can’t win trust without being willing to listen – more ears, less mouth!
In a negotiation, make sure everyone knows what game you are going to be playing beforehand, especially if personal relationships are involved.
Criticism is a dangerous weapon. Used carelessly, the unintended consequences can be serious. Use it wisely and make it appropriate.
Some people play to win, others play not to lose. Having both approaches in a team can be good, but it can be hard for them to understand each other.