Tell your guys that there is never any excuse to miss a service return off of the opposing female. Similarly, they should never DF to her.
I think the biggest adjustment for guys who don't play much mixed is that you cannot stand there just waiting for your partner to set you up at net. Not gonna happen. You have to be active and a men*ace (how come this board considers "men*ace" to be an obscenity) up there. No matter how weak the female's serve seems to be, your guy should be faking and poaching and being as unpredictable as possible.
If they have a drop shot, this is an excellent play against the opposing female, provided they follow it to net.
Use spin, spin, spin. Also, don't be afraid to rally against the opposing female. It is tempting to try to crush the ball ("How dare she return my ball?!?"), but just use spin and angles to make life difficult.
-- Random Error Generator, Version 4.0
-- Master Moonballer