Authorities recommend arriving two hours before international flights. I say four. Get there four hours before your flight. You are a hundred and fifty years old. Your friends laugh at you. Have patience.

Arrive early and move through the airport like the Dalai Lama. You are in no rush. All obstacles are taken in stride, patiently, with a smile.

I really like what Craig Mod has written here. He flies a lot, most of it international and always feels freshen up—well, ok, that might be due to an exceptional gene pool, but still. 

I honestly had never thought of using a mask, though. 

The mask’s role is two-fold: protect you from the horror that is the air aboard airplanes, and create a microclimate for your nose and mouth.
They say the Dreamliner has a higher humidity (10%-15%) than your average plane (7%). Sure, and there are tiny shaded spots in the Gobi Desert that, too, have higher humidity than those spots in direct sunlight. Don’t mean it’s comfortable.

Read it all, it's worth your 5 minutes.