Here’s a nice tutorial on making rocky terrain from tree bark chips.
modeling
Making a 15mm Graveyard
Here’s a tutorial on making a graveyard for 15mm scale figures. It could easily be scaled up, though.
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.