It is very important part for us. First you should grab a picture of a room or city (preferably at night) and open it in Photoshop.

(1) Image>Adjustments>Channel Mixer
Settings: Gray, 0, 100, 0, 0

(2) CTR L+U
Settings: 75, 100, -25

(3) Image>Adjustments>Selective Color
Settings: Colors: Blacks, 0, 0, 0, +100, Method: Relative

(4) Create a new layer and fill with white.

(5) Filter>Texture>Grain
Settings: 44, 21, Horizontal

(6) Set blending mode to "overlay"

Done!