Belonging to a key industry could help in both cases, but more so in China than in Russia. In Russia even scientists working on important projects during the great purges of the early 30's could be executed or sent off to the Gulags. Stalin still purged his highest level military commanders in the years preceding WW2.

Mao, Zhou Enlai, and other high level members of the Chinese communist leadership were able to save useful members like Deng Xiaoping by sending them to relatively safe positions like managing a tractor factory out in the boondocks. So I guess you could say the best strategy would be showing the highest members your tacit future use to them. Deng did this by having a promising, but generally benign early career in terms of being a threat to Mao. This of course mostly applied to people inside the party, who could be purged from the party, sent down for re-education to the countryside, and/or sent to prison/killed.

In the case of regular joe schmoes during the Cultural Revolution the tactics taken if you were afraid your background would come into question, was to become ultra-patriotic and take part even more in mass spectacles and initiatives. This often backfired as the Revolution went on and people you had "struggled" against began to look for reasons to struggle against you. The real trick it seemed during this time was to find a middle ground in which you could not be seen as one of the classes being targeted or as being a counter revolutionary to the initiative at the time.

Going back to the initial point, most sources I have read usually mention the safety of being a member of the PLA and/or being linked to a key industry that was necessary for Chinese global face projects like (factories related to the PLA) Trains, Airlines, sometimes being a member of the Foreign service, athletes, etc.

The worst thing to be was an intellectual during these times that had been with the party since it's early days or having any ties to the United Front period when the KMT and PRC were united against Japan. Or one of their kids. Or someone Mao thought might have a shot of taking over and stopping the Revolution. Or just somebody everybody didn't like too much.

Good Cultural Revolution Mao was a psycho books

Son of the Revolution - Liang Hang the New Emperors - Harrison Salisbury Mao: a Life - Philip Short Hungry Ghosts: Mao's secret famine - Jasper Becker Prisoner of the State: the secret Journal of Premier Zhao Ziyang

Russia The structure of soviet history: Grigor Suny Kolyma tales - Varlam Shalamov