It’s still too broad to really answer in my opinion. One type of global collapse could be nuclear war or war in general that just erases most of humanity. In that situation you’d probably have to move somewhere where not a lot of people live today or you would die fighting in the war anyway. Another collapse could be systemical collapse. In that case you should probably rather build a community that you can rely on when shit hits the fan.

In general it’s probably good to have skills for how to get food, how to get energy to run appliances and machines as well as knowing how to deal with the environment that you live in.