One habit I developed when I grew psychedelic mushrooms and that also translates well to other contexts is not to breathe into containers that you don't want to contaminate. Smelling a half-used-up mayo jar to make sure it's still good? Don't breathe out into the jar. You're just blasting mold spores and organic material in there. Or so the how-to for growing shrooms told me.
Same goes for touching stuff of course. Don't touch the block of cheese, hold it by the plastic it comes in. Your fingers have mold spores on them too. But I think the "don't touch" part is more well-known than the "don't breathe" part.











