I can't find time to write a full step by step tutorial at this time, next time I make another sig I will try to make one.
I will how ever explain how both were made, as best as I can.
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The second one, the Mick Foley one. Was made using only one image and one render. The image that you see of Mick in the back, is just a regular image I found on google. I applied as gradient overlay. I can't tell what the exact color was, it's been to long, but you get it. Onto the image I placed a pattern overlay in the style of "Scan Lines" if you need help with those let me know I can set you up with some nice ones. TIP: never use scan line brushes. Then I made a never layer, I filled that in with complete black, and then lowered the opacity way down, you can also do this by adding a color overlay. This just makes the image layer darker, so the render sticks out more. The render, I did not cut myself, I got it off of PSD Dreams. All I did to the render was resize it and apply a drop shadow with the setting "5.5.10". Then I applied a 2px border. The text has a 1px stroke on it,and I sharpened it once. Pretty simple graphic.
The shemus one is long, so I won't go into detail. I used a render of chains,and a image of the led titon tron and gradient overlay, and scan lines. Took 4 images of him and layed the circles over them and cut the image out. The the main render which has an outer glow on it and a drop shadow, with a 2px border to wrap it up.