Diving into rendering, and hitting a roadblock..

I'd like to use render layers to render the diffuse colors in one layer, ambient occlusion on top of that, and then a layer for glowing materials.

I don't know how to setup the glow layer though. What materials should the glowing objects have on the diffuse and AO layers? On the glow layer do I add both the glowing objects and the non-glowing objects? How do I blend this layer?