This depends a lot on your preferred effect, what colour scheme you\'re using for the army etc. I tend to wash the sand with brown ink then over brush graveyard earth and bleached bone (or more intermediate levels of brown up to bleached bone if I have the time and inclination. Then add some small patches of static grass. My local GW store has some good examples of different schemes at the counter so maybe check yours out before committing to a particular method.
