@Meso Solly
For my US airborne, I have used metal washers as bases. I start by making a mix of plaster, sand and water that I slap onto the washers. When this is dry, I prime the whole miniature.
The bases are then painted in various brown colors using a wet-in-wet technique and then dry-brushed with lighter colors. Sometimes, I also add mud effects from AK Interactive.
In terms of grass tufts and other greenery, I use various products: Grass tufts, moss & flowers from MiniNatur, bushes and other tufts from Polak. I also use static grass from various vendors in various colors depending on the look that I want to achieve (i.e., dry grass vs. fresh green grass).
What I always do with ready to use grass tufts is to
a) sprinkle some brownish pigment (scraped from pastel chalk) onto the tufts and I either push the dry pigment with a brush into the tufts or I soak the whole tuft with water after applying the pigment
b) dry-brush the grass tufts very gently with a light color like Buff or Pale Sand
Hope this helps,
Thomas