For the mask wearers, also consider wearing goggles or at least glasses.

The ears are a mucous membrane too.

Possibly a good idea to wash hands before using the restroom, not just after.

Try to book seats that involve the longest walk to a bathroom in either direction.

Overall, I’ve always been more worried about airports than airplanes. Your odds of sitting near an infected person are low, but crossing paths with an infected person at the airport is much higher.