I've lost mostly small stuff; a washcloth got away from me while swimming/bathing once, and I accidentally left 30' of Kelty TripTease Lightline wrapped around a tree another time. I was given my first pocket knife at age 4, and kept it through my entire childhood. My mom still had it at her house until I was in my 50s, and then it disappeared on me. Point is, I was always pretty good at keeping track of my stuff.
I tend to buy brightly colored versions of an item (e.g., blaze orange mug, yellow vs red Swiss Army Knife scales) or mark small pieces of gear with a piece of orange duct tape or fluorescent pink cord. I also make some of my own stuff sacks, so my tent stake, tarp, sleeping pad, and 'junk bag' are all orange. The prussik knots on my bear bag line (an almost invisible shade of grey Lash-it) are tied with pink cord, and I'm transitioning to bright yellow Zing-it.
I tend to buy brightly colored versions of an item (e.g., blaze orange mug, yellow vs red Swiss Army Knife scales) or mark small pieces of gear with a piece of orange duct tape or fluorescent pink cord. I also make some of my own stuff sacks, so my tent stake, tarp, sleeping pad, and 'junk bag' are all orange. The prussik knots on my bear bag line (an almost invisible shade of grey Lash-it) are tied with pink cord, and I'm transitioning to bright yellow Zing-it.