I took my first daughter Sydney to NY to meet here Grandpa.
Top tips.
1) Keep the baby awake as long as possible before flying
2) When on board, feed them during the ascent to altitude. As they swallow the eustachian (sp ?) tube will open equalising pressure in the middle ear. Main cause of crying IMHO.
3) Once at cruising altitude, and fed, baby will be calmer but still tired and irritable. Change them and then cuddle them to sleep. being tired they should sleep for the normal max duration. This will maximise the amount of sleep on the plane.
4) Reverse the procedure on the descent to each airport. Equalise their ears !
Also, staff should know you have a small child, so don't be afraid to ask for help. Quiet babies and non-stressed parents is what they want as well.
Good Luck Bud ! Remember to keep calm, babies will pick up on your stress levels. My wife and I found that the best methos was that we took shifts on the 2nd leg of the flight to entertain the baby. That way you each get a chance to rest.