The Land of Counterpane blog has a nice piece on basing figures. We all have our methods, but it’s nice to see how others do it.
Modeling
Making Jungle Trees
The Wargame Terrain Blog has a photo tutorial on making jungle terrain.
Making Haunted Woods Bases For Your Miniatures
Here’s a tutorial on making a Haunted Woods base for your miniatures. THe video is aimed at a single base for a miniature, but I think the techniques could be extrapolated to more general base terrain.
Modeling Swamp Trees / Cypress
Here’s a video on modeling cypress trees / swamp trees.