I suppose it would be mostly practical skills, cooking, fixing things. Usually had to be done by people themselves.
Maybe also mental things like navigating (with or without paper map) and remembering their daily and weekly agendas.
What other things would be a big difference with the people today?
People should definitely do this more often. Makes it so much nicer to receive an actual physical card from someone.
Postcrossing also still exists, nice to send some postcards to random people around the world.