The 'risk' moments on long-haul flights with a baby are getting on and off and takeoff and landing. Having fewer of these to do is preferable. Adult fares are more costly, but most families find them worth it.
Many airlines provide free foreign travel for babies, so they may not require a seat. Some airlines need even a newborn to have their own seat. Usually, 'a baby' means a youngster under two years old, but check.
For safety, most airlines require a child restraint device if your kid is in a separate seat. Travel restrictions for babies differ by nation and airline. Some airlines don't supply restrictions.
Try to get a front-row bulkhead seat outside first class. This provides greater legroom and some airlines provide infant bassinets for tiny children.
Even if you pack little, check before leaving home. Taking items from your baggage and putting them in your carry-on bag in front of other passengers is humiliating.
Flying with a baby is best done in layers. This lets you both adjust to the inevitable temperature swings of flight. Although airports are heated, planes may be cool with air conditioning.
Flying with a baby is easier with a carrier. Being near to you will reassure your child. This frees up your hands for older kids and plane travel paperwork.