Terrain design in generic terms.
City Decoration Design
Once the houses and fences and walls are all down, usually I just look around and add stuff that would be there, like dustbins & wheelie bins… maybe a garbage model under them.
Then in backyards I use stuff like old crates and wheelbarrows, buckets and mops, the chopped woodpile and axe and chopping block models, maybe kids see-saws… all that sort of small stuff mostly in back yards.
You can use the Avenue script to string out objects along the roads (requires road network which usually is not available) regular stuff like lampposts or whatever, or add randomness for maybe some occasional roadside veg.
There is a few different garbage piles you can sneak in here and there for more industrial areas, a few different pallet stacks, stacks of pipes and timber.