This video describes how to build some terrific looking desert and Martian terrain.
Modeling
Making Acacia Trees
WarFactory has a tutorial on making African Acacia Trees.
Basing Figures With Baking Soda
A mix of baking soda and super glue can be used to make finely textured bases.
Using Sculptamold To Make Wargames Terrain
I have used this stuff for years. It’s amazing.
Making Pine Trees
The All Hell Let Loose Blog has an article on making 6mm pine trees.