Here’s a tutorial on making a graveyard for 15mm scale figures. It could easily be scaled up, though.
Modeling
Working With Tree Armatures
Here’s a good tutorial on working with tree armatures.
Making 15mm Hedges
Here’s a tutorial on making a 15mm hedges.
Cutting Form Hills Tutorial
Here’s a useful tutorial on cutting foam hills.
Old West Buildings Tutorial
Cowtown Chronicle offers an extensive tutorial on building Old West buildings.