I am a good few inches taller than a friend I am staying with. At home, I never adjust the height of the shower head as DH and DC are taller than me, and it didn't seem to matter. But having it a few inches lower just above my head at my friend's has greatly reduced the time it takes to rinse shampoo and conditioner out of my hair.
I posted this one on another thread recently but worth repeating:
I'm a fairly frequent flier but only recently realised that putting all the things you need to take out of hand luggage and put in the tray at security (liquids/kindle/tablet etc) in a carrier bag inside your hand luggage makes it so much easier to juggle, and you're less likely to miss something .
I appreciate that neither of these things are going to tackle major world problems and may be things everyone does already but I'd love to hear other similar 'discoveries'.