Here’s a nice tutorial on making a forest for your 28mm figures.
modeling
Making Flexible Roads
Tabletop Terrain has a tutorial on making flexible roads for your 15mm miniature wargames out of weed fabric and liquid nails.
Advice on Modeling Rivers
Tim Marshall has some advice on modeling rivers and other bodies of water. There are some very good ideas here.
Cheap and Easy Rail Fences
The “My Wargaming Blog” has an article on making cheap and easy rail fences.
Building An Inexpensive Game Board
Here’s an instructional video on building an inexpensive game board.