I used to fly a lot, being in Regional roles, mostly within SE Asia and Dubai, plus 2 or 3 a year to France or UK so I have a few routines.
Never fly in the morning if you can avoid it, unless you can take gin and tonic at breakfast.
Never wear formal trousers, pack those and wear easily laundered chinos or similar - you don't want to look a peasant in rubbish strides
Have a gin and tonic in the lounge before boarding
Skechers footwear that slips on and off easily for security
Sony WH noise cancelling headphones
iPad with movies already in case the IFE is out of action
Be courteous to the crew
Be at the gate early - you don't want to board last and have the glares from the people you are delaying
Long haul, drink until unconscious.
Overnight flight, change into PJs or similar
Go up the pointy end if you can