The Wargames and Railroads Blog has a nice article on how to paint a WWI US Marine. Very appropriate in this, the 100th anniversary of the start of the Great War.
painting guide
Zombicide Figures Painting Tutorial
Massive Voodoo has a nice tutorial on painting Zombicide figures.
Painting 15mm WWII Airborne Video Tutorial
For Flames of War.
Painting British Infantry
Great Escape Games has a tutorial on painting WWII British Infantry.
Fallschirmjager Camouflage Painting Tutorial
sixtwentyeight blog has a tutorial on painting fallschirmjager camouflage.