Adequate clothing is a start, including protecting your face (I frostbit my nose inAntarctica by not wearing a neck gaiter for 1/2 a day that covered my nose).
Adequate hydration is also key to avoiding frostbite. On Everest, supplemental oxygen also helps. Both help to keep your blood thinner and moving through your system.
Having your mates check your face, etc. is also key to helping to avoid it.