May we introduce to you an exciting new training video brought to you by Eat 3D.
The instructor starts off by explaining the very fundamentals of using Photoshop for texturing. From there he goes into depth on how to set up your high res and low res meshes for rendering Normal, AO, and other Maps.
Once the scene and basics have been defined it's on to the entire texturing process of the self contained scene.
This video has almost 5 hours of teaching and demonstration that will serve as the ultimate texturing resource.