
First start with your sig dimensions (I have mine set at 475x120)
Press D on your keyboard and get some good grunge brushes. Then start brushing to get something like this:

Now go to Layer - New Adjustment Layer - Color Balance and click ok on the next window. Apply these settings:
Midtones: -60, 67, 74
Highlights: -2, -46, -36
Shadows: -54, -58, -83
and click OK
Now go to Layer - New Adjustment Layer - Color Balance again and click ok on the next window. Apply these settings for the new color balance layer:
Midtones: -42, 100, 100
Highlights: -25, 38, 83
Shadows: 68, 4, 51
and click OK
Make sure your second color balance layer is selected and go to Image - Adjustments - Brightness / Contrast and set both options to -100.
after you have those two color balance layers you should have something like this:

Now make sure your background layer is selected and go to Filter - Blur - Gaussian Blur with a radius of 3 pixels.
Now go to Edit - Fade Gaussian Blur with an opacity of 100% and a mode of Lighten.
Your image should now look something like this:

Now you can start putting images and text in there.
here is one I made:
