Not really a rule of thumb, but a recommendation
When cross wind landing, avoid excessive and rough aileron application, roll spoilers will start deploying and you will induce yaw/rolling motions that will screw your ldg up.
I guess it applies to most modern planes, but I´ve noticed the 757 is preety sensitive to aileron and it gets especially crazy during x-w ldg.
Hope it helps.
[ 26 December 2001: Message edited by: Hollow Blade ]</p>