Pack Disinfectant Wipes
It goes without saying that airplanes aren’t the most sanitary things on the planet. Sure, the cabin crew wipes down tables and vacuums the aisle, but they don’t exactly deep-clean the plane very frequently. So, if you want to prevent picking up germs from previous passengers, take a pack of disinfectant wipes with you.
Disinfectant wipes are 100% foolproof, but at least they’ll eliminate the majority of nasty, nasty germs on your tray. You might also want to wipe down the armrests for good measure since nobody would think to clean them unless they’re caked with gunk. Also, wear a mask.