How to shoot night images properly .
1) Shooting high ISO ( 1600 film speed & higher ) handheld camera operation. Turn on your IS ( Image Stabilization for Canon ) & VR ( Vibration Reduction for Nikon ). Turn on NR ( Noise Reduction ). You can always cut noise using the features of your DSLR. Higher film speeds means more noise and lower image quality. With a Nikon D7200 or Canon 70D your night images would be better because of better sensors. If you have an older camera like a Nikon D200 or Canon Rebel T3, you can compensation by using a prime lens ( fixed focal length ) with an minimum aperture of 1.8 or 2.8. This fast lenses tends to be expensive.
2) Shooting low ISO ( 100 film speed period ) on a sturdy tripod. Be sure to turn off the vibration feature of your camera body ( Pentax, Sony ) or the the VR or IS button on your lens. And use a remote to activate the shutter mechanism or use the delayed timer. Even better use the mirror lockup feature in your camera. The last thing you need is vibration on your longggggggggggggg expsosure.