The tips in this video for modeling California Desert bases also could be applied to making various bits of terrain. I have some friends who are currently painting up a Zorro game …
desert
Desert Mesa Modeling
How to make a Desert Mesa for your miniature wargames.
Making A Desert / Wasteland Terrain Cloth
The 1000 Foot General has a tutorial on making a desert / wasteland terrain cloth.
Modeling Desert Wadis
Here’s a nice photo tutorial on modeling desert wadis.