I get my hair blown out before a flight, and then put it into a low, loose pony to sleep in.

As for my face, I am a huge fan of the hydrating paper masks in-flight. After dinner, brush teeth, remove make-up, put on some eye cream, put on a paper mask at my seat, put my seat into a medium recline mode and enjoy a chamomile while watching a movie or something on the IFE for 15 minutes. Remove paper mask. Rub the hydrating ingredients into face, then follow up with face cream and hand cream, and a good amount of lip balm. Put seat into full bed mode. Sleep. You'd be amazed at how much of a difference it makes.