For many of us, making a full lunch in the dark before a 7 a.m. flight is probably not going to happen. But you can—and should—tote along an empty water bottle. Fast food places will usually fill it for free, says Geraldine DeRuiter, the blogger behind The Everywhereist
. Try not to look too smug—or hydrated—when you see you fellow passengers dishing out $5 for an Evian 10 feet past the security checkpoint.