Dice4hire's paint on moss looks very good.
I would also use flocking.
Water down your white glue to about 50%. A little flocking goes a long way.
A few leaves are also effective. Colored paper with Green stuff Word punches
Use lots of color.
Use more than one texture
Combine water effects and paint.
Build up the effects
Use ink washes
I make my own washes
Grass and moss need light to grow. You will not find it in the dark.
OldmanWillow AKA OldEnt. Customer and fan from 1996 onward!