Nighttime photography can produce some stunning images but it can also produce some right doozies.
Issue 82 of Photoshop Creative looks at five of the best tips for improving your night shots. Here’s one to get you started:

Darken the sky

Night shots are actually best taken after sunset when there’s still a little ambient light in the sky. This may mean that the sky ends up lighter than might be required to accurately convey a sense of night. In this case we can make improvements by darkening the sky and perhaps adding a little more colour saturation. Add a Hue/Saturation layer, select Blues from the drop-down menu setting Saturation to +90 and Lightness to -75. Brush out the effect with black on the layer mask if other areas of the image are affected. To increase the strength of the effect, simply duplicate the Hue/Saturation layer with the shortcut Ctrl/Cmd+J.