My experiences - travelling with baby @ 3 months (Roundtrip Long Haul 12Hrs++), @ 4 & 5 months (RT Short Haul 3hrs++)
Tips:
1. Maghanda ng milk ni baby either BM or formula. If you are using BM, see if you can ask the FA kung pwede makilagay sa chiller nila, lalo pa pag wala kang bitbit na cooler. Useful din ito pag balak mong mag-express during the flight.
2. Make sure you have your pumping tools if you plan to pump during the flight. And beforehand, inform the FA na mageexpress ka para ma ipoint ka nila sa pinaka spacious na toilet sa eroplano, or at least inform the passengers if there is a queue forming outside the toilet dahil nageexpress ka. Bring your nursing cover na din just in case hindi ka maka-express sa toilet, and make sure you choose the window seat para di masyadong obvious kung kailanganin mo ngang mag express whilst in your seat.
3. Compress your diaper bag into a diaper kit (parang toiletry kit) containing super essentials lang and put that inside your carry on bag. As much as possible i limit mo yung carry on baggage mo dahil the last thing you want is keeping an eye on so many things including your baby. Once on board, you can just take out her "toiletry kit" and keep that by your side.
4. Before you fly, make sure you call the airline to assign you a bassinet seat and if possible request for a bassinet. With infants for example you have to pay 10% of the normal ticket fare. Dapat mong sulitin by asking for a bassinet seat/bassinet.
5. Take your pram hanggang sa boarding gate. Some pram models have their own carrying cases/bags, kung meron or wala ka nun, make sure to ask the handlers (I'm sure they will) tag it properly and give you a plastic bag to wrap your pram in. Que sa boarding gate or check in sya, kung hindi sila maingat, masisira at masisira talaga ang pram. I know for some airlines, at the boarding gate, they just give you the plastic para ikaw mismo ang magbalot ng pram. Hassle, lalo na kung mag-isa ka lang na magtrtravel. Patulong ka nalang.
6. Personally, di ko nagamit ang baby carrier ko dahil most of the time nasa pram sya or kung hindi man, nasa bassinet. Kung wala sya sa bassinet, karga karga ko sya sa lap ko and kailangan syang suotan ng seatbelt. If you can afford it, travel by business class kasi every time they put the seatbelt sign on, ipapatanggal nila si baby sa bassinet so kahit tulog sya, kailangan mong gisingin. Samantalang kung naka business class ka, pwede mo syang itabi sayo or i-recline ang seat para nakahiga sya the whole time (basta naka seatbelt sya).
7. Make sure that you give baby milk at reasonable time before/during descent. I gave mine milk nung nasa 20,000 ft kami para habang bumababa, swallow lang sya ng swallow para hindi sumakit ang ears nya. I must warn you though, na sometimes, kahit may milk pa, sasakit at sasakit talaga ang ears ni baby at iiyak sya. Just try your best to keep calm and soothe him nalang kung ganun. Wala talagang magagawa until you land.