Step 3: Scratches - part 1
Create a new group called "Scratches" and another group inside that called "Metal". Inside the metal group, overlay some tileable galvanized and grungy metal textures with the opacity set low. This is to give some subtle variation to the larger scratches.
At the base of this group create a new Solid Fill layer and select a mid-gray color. Apply a mask to the metal group and fill the mask with black. Then with a white, hard-edged scratch brush, begin painting scratches in the group mask. Try to put scratches where they are most likely to appear, like where the shoulder armor would scrape against the torso - but don't overdo it!
Step 4: Scratches - part 2
Create another group inside the scratches group and name it "Small Scratches". This group will be used to add small surface scratches to the armor. I use a combination of painted scratches and some scratch textures from CGTextures.com.
Duplicate these around the armor and then use a layer mask to paint the visibility of some areas. This will help hide some of the repeating scratches throughout the texture. Set the blending mode to Screen and the layer opacity to between 5% and 10%. We want it to be barely visible, but we'll increase the visibility of the scratches in the Specular map.
Step 5: Lights and Emissive map
This character has some glowing lights and to create this effect we'll be using an Emissive map. Create a new group called "Lights" and put it above the bakes layer. For the circular lights on the back, use the circular Marquee tool to create a circular selection then go to Edit > Stroke.
With the lights painted, right-click on the layer and add a small outer glow to the layer styles. Select a slightly lighter version of the color used for the lights.
Create a new group above the diffuse and call it "Emissive". Duplicate the Lights group into the emissive group and create a new layer under the lights group and fill it black. Increase the saturation of the lights layer with a Hue/Saturation adjustment layer and increase the outer glow.