Make a list of everything you need and stick to it. Things that we have forgotten in the past include tea bags, flipflops (mine), toothpaste, washing up liquid, teabags (again), sunglasses (my prescriptions ones), pillows (yes really), the kettle (although we didn’t actually forget it, I ran it over with the car), gas on which to cook (in my camping days), torches, tea bags (they get a regular forgetting to as do sweeteners/sugar), matches and barbecue lighting fluid (pre cadac days).
All things considered I think that we are lucky to have stayed together considering the amount of time we found ourselves without the morning cup of earl grey. strangely we never seem to forget the wine.