Prepare. Take lots of snacks, drinks, amusements, (see below) on long plane rides – and, really, everywhere you go.
Pace. Don’t try to do too much! Schedule one major activity per morning, or afternoon; if all goes well, you can perhaps slip in a second activity. (Don’t mention the second activity until you’re certain, though – avoid disappointment!). Pacing also means allowing extra time in the day for some down time, and some wild time: kids need rest periods, and they also need to run around and let off some steam.
Pre-empt: offer snacks and drinks before kids get too hungry or thirsty. Take a break before they’re overtired.
Patience: and more patience.
And perhaps most important of all: Play. Have fun with your kids!
Patience actually saves time, in the long run: it’s far quicker to muster an extra five minutes of patience than to spend fifteen minutes coaxing a three-year-old out of a snit.
Remember: even the bad moments of your travels with wee ones will look very precious, once they’ve grown into large-size kids!