Book flights as soon as possible, the early you book the cheaper the airline ticket usually is.
Make sure you have a long enough layover (shortest 2 hrs) to get through security and your connecting flight.
Pack a snack for your flight If you are picky with food.
Pack all electronics and valuables in your carry on.
Before flying plan how you are getting to your accommodation after you arrive in the country.
Not all planes have chargers so charge your devices before flying.
Pack all your medication in your carry on, so if your luggage is lost you will still have your medication.
If possible check in online 24 hours before your flight.
Have electronic copies of all your important documents in case any you lose any of them.
Most airlines let you pick your seats, check if you can right away.
To avoid delays try to pick the first flight out of your main airport.
Make your luggage stand out by attaching a ribbon or band on it.