When I went to China this summer, I forgot how dry a plane can get.
So on my way back, I made sure that I was super prepared and it felt amazing!
A new way I discovered was using milk as facial mask.
Most flights have beverage service, even the short ones. You could simply ask for milk assuming that, and drink most of it. The "left-over" is what you put on after washing your face. Although I washed it off after 1 hour or so, I don't think that there is a huge difference if you don't wash it off.
After that, I could put on facial cream as it suppose to have longer effect.
Here is a summary of all that I have used:
1. Milk, the cheapest way and the only way if you forgot to bring skin-care with you
2. facial mask, the most effective way but it might look weird if it's not a long flight
3. facial cream, a must-have
4. facial spray, the easiest way
Also, you might want to check the restriction for carry-on liquids. I never figured out the actual restriction, but I know for sure that each bottle has to be below 100ml.
Lastly, you might want to choose airlines carefully if you are flying long.
Personally, I find that AirCanada has better entertainment and United Airlines provide more and better meals. I always bring lots of snacks whenever I am with AirCanada.
After all, a long-flight may not felt that long if you are prepared =]
Have fun on your trip!