It's a natural instinct to want to pack every single thing your baby might need for your trip, but the less you pack, the easier the trip will be on your wallet -- fewer checked bag fees! -- and the less you'll have to lug to the airport. Pack only a day's worth of diapers, for example; you can buy more when you get to your destination. And if you'll have access to a washing machine, pack half the clothing you'll need and do laundry halfway through the trip. You can even request or rent items like cribs, play yards, baby gates, bouncy chairs and Exersaucers at your destination; call your hotel or a local rental company ahead of time to reserve them. Most car rental companies offer children's car seats, too.
And remember to keep your carry-on as clutter-free as possible. The less you'll have to rifle through to find what you really need -- and the less weighed-down you are -- the less stressed you'll feel.