Make sure that you pack something that they like to chew... raisins, grapes, peanuts, gummy bears... something to work those jaws and equalize the pressure during take off and landing.
Also, remember if you give them something to suck on NOT to tell them to suck on it. That is, if you want the lifesaver to dissolve on their tounge, tell them to let it melt by rubbing around in their mouth.
I made the mistake of telling my son to suck on it, he inhaled it, threw up when it stuck in his throat, and wound up stinking of vomit all the way to Florida on one flight.
Second, ask the attendants if they have flight wings for the child to celebrate their first flight.
Ask for a pillow, and make certain that you and your child are either on the aisle or that you can get out if a potty break is called for.
Pack some lightweight softcover books or magazines with large colorful pictures for them to "read" during the flight.
consider taking your safety seat on board for the toddler to sit in/sleep in. Ask ahead of time if it's permitted, and be prepared to arrive extra early so that the seat and your carry ons (diper bag, toy bag, etc) can be searched and x-rayed.
Be sure to have shoes that are comfortable for the toddler to slip on and off for the security check, and a push stroller that converts to a safety seat is best. Certainly beats carrying the child through the busy airport.
Carry at least two back up binkies (pascifiers) and two security/soft sleepytime blankets so they can feel something soft and drop off. Don't forget drink boxes.