Before I build, I usually:
go into terrain paint mode and start sketching out where I want the house, the patio, the trees, the bushes, hills, paths, fences, ponds and swimming pools. I also make sure I leave enough space for game play objects such as swings, a vegetable garden etc. and ensure that routing makes sense.
create elevated areas, if any.
build the house, including interior and exterior features such as the patio, sheds and a glasshouse.
fill the garden based on the sketch I made: Fenced off areas first. then undergrowth/flowers, then scrubs and small trees and then bigger trees. Finally I add stones and re-paint where necessary.
Done.