A picture is worth a thousand words, especially if it helps you find your car.
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Take a picture of the contents of your fridge before you go grocery shopping.
It'll remind you what you're missing and what you already have too many of. (I don't know what humanoid rabbits own this fridge but these mofos could really use some bacon.)
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Catalog the stuff you lend out.
Screenshot directions, especially if you'll be traveling underground or anywhere you won't have service.
(I mean obviously never use walking directions that are this ridiculous, but the fact stands.) Just make sure in advance that you'll have data/service if you're traveling overseas.