The best way not to get sick from plane travel is to have your vaccinations up to date... Especially current Flu Shots...and Hep A and B...
Also some other vaccinations if you are going to less developed areas... Make sure your dental situation is good...
A little hand sanitizer seems reasonable...
But a total germ fetish about seats and arm rests...? I don't think so... Of course some people are infection prone...
I always drink bottled water when I'm traveling and I stay well hydrated ...always buy the bigger water bottles...
And don't be too brave about "going native" with foods until you know what you can tolerate... Avoid Raw items...unless you can peel them... Try to order food that is hot...and don't accept a too cool dish... Always go to restaurants that are well lit and full of locals packing in food... Follow the locals when in doubt... Avoid dark empty looking restaurants...
And most of all...be a little Lucky... don't get assigned a seat next to a sick person...!
