I try to have my figure bases and terrain bases roughly share a common basing theme - so for my basing I mix a bit of black acrylic paint into my basing paste (modellers paste or wall filler) to get the white out of it, then once applied and dry, dry brush a light colour to highlight texture. This is just so if any base shows through the subsequent flocking, it look consistent and respectable..
Then PVA and sprinkle with any small rock or ballast, then sprinkles any course sand and then grasses and flock into any PVA still showing. Finally I ad a few blobs of PVA on top of everything and put in a FEW tall grasses.
I don't over-grass WWII infantry as you will want to see them in towns, but grass them enough that they will fit against my other terrain pieces.
For my tree bases I also drag a few strands of hot glue from the tree trunk bottom outwards, that when dry can be painted as tree roots.