There are a lot of topics on this community on people asking how to prepare for a long haul or people complaining about crashes during these flights.
Here is how to get ready for a long haul+ flight:
1: Make storage on your device if needed
2: Clear Scenery cache (In settings on infinite flight)
3: Choose an aircraft with long range (787 family, 747 family, 777 family, a330, Md11, C175)
4: Dim brightness
5: Mute device
6: Plug device in during entire flight with a GOOD QUALITY CABLE
7: Launch flight
8: Lots of fuel, less passengers and cargo
9: Choose good Flight Plan and Altitude.
10: Set timer so you do not forget your flight
12: Live a normal life but checking on the flight from time to time with Liveflightapp.com or look at your device
Have a safe flight!
I hope this helped!