The League of Ordinary Gamers has a quick and easy idea for making some good looking 15mm barbed wire.
The Lights Are Going Out is a set of free wargames rules for WWI in 1914. The rules are designed for 15mm figures.
18 Charlie has a tutorial on making 15mm palm trees. The methods looks good, and should be quick and inexpensive.
Here’s a tutorial on modeling 15mm wheatfields for your wargames terrain collection.
The key ingredient in this project are door mats made of coconut matting, called coir matting.
Zrune Lord has a brief photo tutorial on painting a 15mm orc. I find it interesting that he uses inks on his 15mm figures. I’ve never tried that, instead relying on blocking and dry brushing.