It's about not being afraid to visibly step into the court to receive serve when you see your opponent struggling with their second serve.
It's about not being afraid to show a positive emotion if you win a point from a net cord (even though you hold your hand up), rather than being so apologetic that you are guaranteed to lose the next point.
These are some of the traits of winners -- so use them.
Lose Your Fear of Losing and Winning
One of the biggest downfalls I see in doubles teams, and tennis players in general, is the fear of both losing and winning.
Most players don't really understand the differences, and as such, they don't know what to do to avoid them. So let's change that.
Fear of losing tends to occur in situations where you are supposed to win -- like when playing a pair with a lower rating or ranking. You get so wrapped up in worrying about what people will say if you lose this match that the freedom you would normally play with and the freedom needed to play well is strangled along with your game.
Fear of winning can happen when you find yourself in a winning position against a pair ranked or rated higher than you. You somehow don't believe that you can or should win the match because this team are better.
In both situations, you find that confidence and self doubt become an issue -- and we all know that playing with confidence issues makes winning very difficult.
Don't allow yourself to think about winning and losing (an outcome) and only worry about how and why you will play the next point (the process).
Constantly talk to each other about your game plan and your jobs on the court and never talk to each other about the outcome.
Discussing the ball and what you are going to do with it will stop you from drifting towards the end of the match, which will naturally lead you to start thinking about winning or losing and will cause you to drown quicker than you can spell "choke."