Choosing your subject matter
Anything that is lit up, like fountains, buildings, monuments and bridges work well. Skylines, especially if there is water to create a reflection, can look spectacular. Look for reflections and neon signs and play with light and shadow.
Try capturing scenes through windows of shops or restaurants. Can you find a place that is normally busy during the day and portray it differently? Other subjects that lend themselves well to night-time photography are fun fairs, ferris wheels and fireworks. Use a slow shutter speed to create light trails. Find a place where you can photograph passing traffic or public transport and experiment. Think about the atmosphere you are trying to create. Are you are capturing things that appeal to you or creating a mood or telling a story?
If you want a very slow shutter speed, and sharpness is important, using a tripod will enable you to decrease your shutter speeds as much as you like. Remember to turn off image stabilisation and to use a remote shutter release, or set the timer on the camera. Even though it doesn’t feel like it, just pressing the button can cause your camera to vibrate, reducing sharpness in your image.
A wide-angle lens is probably preferable for night-time photography. Normally, to get a sharp shot, you need to choose a shutter speed at least equal to, or greater than, the focal length of your lens. For example, if you are using a 200 mm lens, your shutter speed should be 1/200, or faster, for a sharp shot. You will have to adjust your aperture and ISO accordingly and you might not want to work within that range (losing depth of field, increasing grain). Conversely, with a 50mm lens, you can shoot upwards of 1/50 of a second.
Modern cameras allow you to use a much higher ISO. At a certain point, the final image will have get grainy but, overall, you will still get a good quality image. Experiment with the acceptable limits of your camera and find out what level of grain you are willing to accept. You can reduce grain by using post-processing techniques. In Lightroom, for example, there is a “noise reduction” section and to increase luminance. Be careful not to go over board or your image will look unnaturally smooth and artificial.
Last but not least…
With street photography, particularly at night, you may encounter people who are curious, or even suspicious about what you are doing. Know the rules that apply in the country or place where you are shooting. Remain friendly but move on if you feel unsafe. Make sure that someone knows where you are and carry a torch and /or fully charged phone. Enjoy getting out there and trying something new.