mix flaperons/spoilerons to a slider or variable control on your radio if you have one. I run fairly extreme settings, the flaps/spoilerons are at max travel of the servo, so full down flaps will only use one servo for aileron inputs.

I've also tried mixing elevator halves to aileron, that almost cost me a plane! I suddenly acted like it was extremely tail heavy in turns. the tail would dip and it would bleed off airspeed, stalling it every time, even when in normal speed flight.

other then that, some people mix rudder to elevator to correct KE coupling. if you have variable flaps you can accomplish this to some degree already, so I've never found that mix to be of much use.