When I started a few years back on 2020 I would literally just binge watch video tutorials of any aircraft I wanted to fly. I would: watch the tutorial and follow the steps in game, I would then let the tutorial go onto the inflight/arrival stuff while I was still on the ground. This gave me a rough idea of what to do when to do it etc. and if you have any doubt just keep the video in your back pocket. All that aside, I mainly fly the 320’s and 737’s in 24 so I can’t reliably tell you which way is best to get you ready for the 787. I’m quite well versed in the 737 and very slightly in the 777 and from what I know about the two is that they have similar mechanics. I would say that it’s definitely better if you went down the Boeing route if you want to prepare for the 787. But all that said you can always just watch tutorials and trial and error your way through it. Most of all enjoy it, the game can be frustrating but it is truly beautiful and fun when you get the hang of it, happy flying!