Remember to pack a pen
Even if you don’t consider yourself a budding novelist or a crossword fan, you should always pack a pen in your hand luggage when you’re traveling. You might not need it, but you never know what kind of situations you may find yourself in. Perhaps you need to fill in a visa form or sign something, and you can’t walk around the airport looking for a pen.
And let us tell you that filling in customs forms with an eyeliner pencil isn’t considered very professional. Besides, if you’re stuck with nothing to do for hours, perhaps you can consider starting to write your life story or a new novel. Or, at the very least, doing some doodling while you wait to disembark at your destination.