Buy Some New Socks
Lots of people like to kick off their shoes on flights, especially long ones where you’ll be sleeping. Perhaps this is a good occasion to buy some new socks? The last thing you want is to accidentally stink up a plane, since it’s not like anybody can open a window to bring in some fresh air. If you're willing to go a step further, consider putting them on in the bathroom before you board your plane. Another thing you can do is dust your soles with a little baby powder to mask any smell.