Theres a couple of options you can look at.
If you're shooting handheld, I would really recomend getting a tripod if you want to do a lot of night shooting, long exposures will really give you the brightness you need for a night shot.
If you're not looking to get a tripod, try adjusting your shutter speed to 1/focal length and bumping up the ISO (if necessary). If you have any lenses with wide apertures (F/2.8 or less, primes for example) you can use those to shoot at night, although you're going to be getting a lot of bokeh and you're going to have less depth of field. You can also try a lens with Image Stabilization, as IS will help reduce camera shake so you can shoot at longer exposures, which can help. You could also try to use an external flash unit (which I'm currently waiting on, so I can't exactly give the best advice on flash photography) but you'd have to figure out an angle for the flash so you wouldn't get abnormal shadows and washed out colors. Honestly if you're really looking to do a lot of night time photography, a tripod is the way to go, and I'd recommend the Bogen/Manfrotto 3021BPRO with a 488 RC2 ballhead (what I have), very sturdy tripod, a little heavy but its solid.
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