new phone and or watch or both

[stewarta13wsb]

OK newbie question although not a newbie, sorry.

Each time I change my phone (more often than I should) or have to reset my watch, I seem to lose Samsung Health history and some watch faces.
My P20 Pro is going when my Note 9 is delivered and I'd like to get it right this time. In addition my Galaxy Watch will be here soon too, which doubles the chance of me screwing up. What's the foolproof way to get this right, assuming the watch come first(?)

EDIT: Got that the wrong way round, it'll be phone first!

 

[Darth Mo]

As long as you sign in on your current phone, it will back up your data. When you get the new phone, just log in again and it should restore everything.

That's all I did and it was fine.