A couple of tips from my own experience.
-Have a checklist, so you don't forget stuff.
-Packing cubes make packing a bag much easier.
-For long flights with a stopover (e.g. Europe to NZ) you can stay in a transit hotel in the airport terminal. This means you don't have to go through immigration, security etc. So much easier than having to travel out to a hotel.
-I have found Airalo to be quite good for local data esims.