I love old neon signs. I found these in Union Station in Portland, Oregon.
First decision: which lens? I wanted narrow depth of field to make the TELEPHONES sign stand out against a blurred background, so I used an 85mm lens at f/1.4.
The untouched image is still a long way from doing justice to my subject. Old neon signs make me think of film noir, but there's no sense of darkness, menace or mystery in the photo. And there's boring empty space on the right-hand side of the frame, while the heater and trash receptacle intrude at the bottom. (I wasn't able to frame the image more tightly because I would have lost too much of the interesting reflection on the left side.)
So cropping is the first order of business. Apart from removing unwanted elements, the crop also creates interesting geometry - the image is now composed of three vertical strips.
The remaining adjustments aim to further enhance the prominence of the neon signs - especially "TELEPHONES" - and to create a more dramatic "noir" ambience. I blurr the background further through fine-contrast adjustments (a tool available in DxO Photolab). I adjust color and lighting to increase the intensity of the neon signs while darkening and desaturating much of the background.
In the untouched photo it is obvious that the shot was taken in daytime, inside a public space. But the adjustments have removed evidence of time and place. The scene now now has an air of mystery. It looks as though it could be anywhere, any time of day.