I personally will use dilutted GW scrotch brown to paint all over the sand; then drybrush / highlight the sand with GW Terracotta, it is a red-like brown.
Folks, pls share with me if you get any other tips; teach me if you do not mind. hehe
Most "red desert" settings highlight out to a salmon/pink sort of color more than vermillion/orange. Try that. Oh, do a google search for images of the grand canyon and you should get some great examples.
"I like gypsy moths and radio talk
Cause it doesn't remind me of anything"
I remember some time ago (damn long time ago to he honest... ) I tried to create red desert for imperial wolves from good'ole warzone game...
I remember I experimented with car sprays but can't say that was exactly what I wanted to achieve