One thing that I would recommend is paying VERY close attention to the drone while flying at those sorts of altatudes. The air is pretty thin up there so the drone may behave differentially. Don't get carried away taking photos, keep your eyes and ears open (often if its quiet you can here if the drone is doing something it shouldn't be, even if you can't see it) if you can see your drone while your flying I strongly recommend watching it at least as much as the screen, just keep flicking between the two.
But definitely do take plenty of pictures and videos
and don't forget to share them here, we would all be very interested.
Lastly, get as much experience beforehand as possible.
But definitely do take plenty of pictures and videos

Lastly, get as much experience beforehand as possible.