The Spellscape blog has a couple of good tutorials on painting skeletons. They look absolutely terrific.
painting guide
Painting WWII US Paratroopers
Mage Knight Kevin has a nice photo tutorial on painting US paratroopers from WWII.
Ancient and Medieval Painting Guide
Here’s a nice — if not overly deep — painting guide to ancient and medieval armies.
Painting A Confederate Regiment
Ministories has a step-by-step photo story on how to paint a regiment of American Civil War confederates.
American Civil War Painting Guide
Quindia Studios has a basic American Civil War painting guide.