A successful doubles team is usually one that communicates well. An earlier posting talked about laying out a specific match strategy before taking the court; and here we look at communicating during the match.
As much as possible, I believe you should limit your conversation during play to “match strategy” and NOT a critique of your partner’s tennis strokes. During a match is not the time to try to improve how they hit a forehand or a volley.
You should continually review what your scouting report on the opposition was and what your game plan was to deal with their strengths and weaknesses. Are the things you planned on doing working? If not, is it because you are not executing well … or, are they doing something you had not expected?
For example, if their serves are stronger than you had anticipated, maybe you should receive serve “two back” on the baseline to get into the point better. Or if they are lobbing you a lot, take actions to take that away from them.
Basically, if you are losing, quickly ask yourselves the critical two questions: “What is happening here? And, what can we do about it?”
And try to never get mad or visibly upset with your partner if he misses a shot. We are all human and that will happen. What you want to continue to talk about during that match is what you are doing that is successful and what is not … and continue doing the first and change the second.