DON'T DRINK THE WATER
Drink bottled water to safe. The storage tanks for the jet's "tap" water are difficult to thoroughly clean, and studies show bacteria like E.coli can linger in them. Skip coffee and tea, some airlines make it from that water. The ice is okay, though because it's catered.
Planes pump out a 50-50 mix of recycled and fresh air. To ward off airborne nasties, turn your vent on low wipe down the nozzle with an alcohol wipe first, and point it toward your lap to blow potentially infectious particles away from your face.
The Tray Table
They contain nearly 10 times the bacteria of a toilet flush button, per a Travel math study. One reason: People change their kids' diapers on them. Bring alcohol wipes or use a couple of drops of 60 percent alcohol-based hand sanitizer on a tissue to disinfect yours.
The Blankets and Pillows
If they come in a sealed bag or you had to pay for them, they either haven't been used before or were washed, so snuggle up and get comfy. If not, they were likely used before and tossed in the overhead compartment without being cleaned.
More carriers are going toward a leather type material that's easily wiped down. If you're skeeved out by an old school paper cover, remove it or drape a jacket over it though know this: There's zero evidence lice are spread from these, despite rumors to the contrary.