Niko and Colm: Hmmm, I'm not too good at giving advice, lol. But, instead of using a lot of light on it, to make the sig focus on the render, i try to lighten it a bit, and use the sharpen tool.
To get those transparent borders, i make a new layer, and brush the top and bottom with a custom brush i made, using it white, then i set the layer to overlay.
On the New Super Mario Bros. Bumblebee, and Paper Luigi ones, that effect? Is the flame render you can find by clicking Filters >> Renders >> Flames. The hard part is, you'll need to search through everything and find a good render to use, once you find a good one (make sure it has it's own seperate layer) sharpen it, and set the layer to screen.
That's all i have to say :s