A. Imrie has an extensive set of tutorials on painting figures with the non-metallic metals technique.
Here’s an interesting concept: highlighting figures in fluorescent paints. It looks like it works well for fantasy and science fiction figures.
Laszlo Jakusovszky has a tutorial on painting fire. Now you can do justice to those flaming pigs models that you’ve had in a box for years.
The Hot Lead site has a tutorial on painting wood textures.
Here’s a handy chart for converting between Vallejo and Games Workshop’s Citadel Color paints.