Get your first serve in. It puts less pressure on your second serve, and makes your opponent have to work harder. Your percentages go up for winning the game.
Develop a second serve that isn't easy to attack. Again, your percentages go up.
Percentage serving means serving the T on the deuce box and body in the ad. Those placements take away angles and keep your net partner in front of the angle of return.
Hit good cross court return of serves that are difficult to poach and force your cross court opponent to stay back or hit up.
When returning a fast server, try taking the return early (inside baseline) with a block backswing and counter the pace away from the net player. Try standing way back and lob, or stand just three feet behind the baseline and and take guided short swing. You will have to try different things to get into the point.
When returning a soft serve or easier kick, shorten your swing, chip or drive and take position beside your partner about one foot inside the service box. If your team can take a position inside the service boxes, and volley the ball to a groundstroke of your opponents you stand a 65 to 35 % chance on winning the point given equal ability levels. Take the ball in the air!
The player in front of the opponent striking the ball should be closer to the net to be able to poach if needed. The partner has to take a position that is either off net at the service line or baseline to cover lob threats.
When both players are at the net, the diagonal player takes the middle volley. When both players are back, the stronger middle shot takes the middle ball.
When lobbed over your head and out of reach, concede your offensive net position, switch to the other side, while facing opponents, and retreat diagonally to the service line or back court depending on the time you have.
When taking non-obvious overheads, tell "me or you" to your partner early, so that proper court positions can be maintained.
If your partner or you can't clear the net player then your team should start both back to defend smashes.
If your partner hits a good poach or volley, approach to the service line and join them in a staggered net position.
If you approach the net take a position one foot inside the service line and split step.
If you hit a baseline shot take a position two feet behind the baseline.
Communicate some obvious priorities (tactics) but don't over complicate things. Be supportive and upbeat no matter what with your partner.
If you and your partner are playing a team that has good lobbing ability then take a position off the net more then you normally would if you are the server's partner. Also, if you do approach the net together, hold up a t the service line, parallel with you partner so that you both can cover deeper lobs easier. If the ball does get over your head, yell "you" and switch to the baseline with your partner now returning a lob, allowing you both time to reset in a defensive baseline position. Your goal here is to stay in the point and patiently wait to you get an opportunity to take the net back. Hopefully your team will be able to hold the line with overheads more than you must retreat and concede the net to your opponents.