Massive Voodoo has a nice essay on keeping your brushes clean.
Painting
Painting 15mm Horses Tutorial
Anatoli’s Game Room has a tutorial on painting 15mm horses.
Painting A Lord of the Rings Dwarf Model
Kevin’s Miniatures and Hobby Table has a photo tutorial on painting a Games Workshop Lord of the Rings dwarf.
Painting Rust Effects
The Man Cave has an article on painting rust effects. Lots of good techniques here.
Complete Guide To Getting Started In Airbrushing
The Leadhead has a very nice article on getting started in airbrushing. Well worth the read.