With infants you cannot afford anything to go wrong because everything itself usually turns out wrong with your kids around.

Make sure the flight is on time by calling them a few hours ahead.

Ask for bulkhead seats, which allow for a little more leg room that makes it easier to move around with your baby.

 If you can afford it, buy a separate seat for your child, especially if you're on a cross-country or international flight.

 Pack plenty of supplies, including snacks, formula, diapers, wipes, bottles, sippy cups, etc.