Travelling with my 4.5 month old for the first time! We're flying to Europe on a 13 hour flight. What are do's and donts of flying with a 4 month old? Any tips much appreciated!

I've seen mommies wanting to breastfeed baby during takeoff because it helps with the pain in baby's ears but with the infant seatbelt/harness and safety regulations, it might be difficult. My friend would nurse baby before takeoff so baby would sleep throughout the harrowing experience.