This is How sigs are generally made up and in this tutorial you can re create the Hulk/ Rooney sig below.  Assuming you know the basics of Photoshop I wll be frank with the explanations. TIP: Always add layers when making changes because if you paint on a layer accidentally, you won't be able to correct it later.

Thes are what Ive started with. Both images are on their own layer with an original background layer behind them. Sig size 400 x 130 Pixels.

Add some brush effects and filters like gaussian blur to the background.

Same again on another layer, you can choose your own layer effects too.

Click the eye icon to hide the brushed layers, then drag the Rooney layer onto the Hulk layer, reducing the opacity so you can see where to place, then resize and rotate to fit.

Use the eraser to rub remove half of Rooneys face and tidy up with the clone tool, add some brush effects to the shoulders, brush on the background and set the layer to screen.

Duplicate the Hulk rooney merge. I used some plug-ins to get the thatched effect for use in the background. set the layer to hard light and reduce opacity to 35% then i put it under the previous layer.

On a new layer, add some brush effects using the colour picker to select colour from the hulk and rooney and paint around them. You can adjust the layer properties to your liking.

Next add a border and Rooneys Tongue, I used the paintbrush and painted my own reducing the opacity on each layer to get it how I wanted.

Finally add your name, copy the name layer and add motion blur to it. Then you need to apply the image (image,apply image) and adjust using curves to get the final result you're after. You can always keep going if you want with different layers and effects to get the desired effect.  As you can see the possibilities are endless.

Advanced Tutorial

Ok so now hopefully you have the jist of the basics and in this tutorial we will get slightly more advanced to get effects with light and C4D (Cinema 4D images) easily found with a quick search in Google. So lets get started.

Step 1: Create a new document 400 x 125 and fill with a purple to black linear gradient going from top to bottom.

Step 2: Add your render, you can use whatever you like, in this case I've chosen a character from the game fist of vengance and placed her off centre.

Step 3: Copy your render layer and adust to Hard Light with 53% Opacity.

Step 4: Add some C4D and delete what you don't want then set the layer to Overlay with 88% opacity

Step 5: Copy the C4D layer delete some more from it and set to Overlay with 60% opacity

Step 6: Add some more C4D and delete around the render, just leaving the effects on her costume and body set to overlay at 100%

Step 7: Now you need to add a new layer with nothing on it then go to Image, Apply Image. Then get some Red C4D images and place them on a new layer. Set layer to Overlay at 94%

Step 8: Copy the Red Layer and position it at the bottom of the sig then set the layer to Screen with opacity at 60% then add a different type of C4D image, the one I used had Bubbles on it and I positioned that to the left of the render.

Step 9: Copy the previous layer and position it to the right of the render and leave the layer effects the same.

Step 10:  I used the Red C4D layer 3 more times deleting around the model and set the layers to Screen 60%, Overlay 94% and Overlay 50% then I added another C4D image with the large ball shapes and set to Overlay at 49% and deleted around the render to get the following look.

Step 11:  Next was to use some brushes downloaded from the net, I brushed over the  render on a new layer and deleted around her body and head to get the following then copy your star layer and deleted some more around the Image until you are happy.

Step 12:  Add another C4D image to get the flash going accros the chest of the render and set to Vivid light with 46% opacity. Delete what you don't want.

Step 13:  I added some more small star brushes then set the layer to Pin Light and set it at 84% opacity.

Step 14: Next use a star brush on the shoulder of the render and around the chest area then set the layer to overlay at 88% Delete unwanted areas of the brush.

Step 15: Again go to Image, apply Image and tidy up using a soft eraser tool. Keep the layer on normal at 100% and reduce the opacity of the brush before erasing around it.

Final Stage: Simply add your frame and Text if required. That's it!