Key problems:
1) Keeping camera stable
2) Image noise
Tips:
1) A tripod or other support to keep it steady
2) Set larger aperture and turn off camera flash
3) Set your camera 10 second self-timer
4) Select your camera landscape mood which ensure current focus
5) Select camera night scene mood
Link:
http://stylepeterson.com/photography-articles/night-photography-tips
http://dptnt.com/2008/10/night-photography-ideas-and-techniques/
http://www.goodphotography.info/intermediate/night-photography-tips/
My Learning Bible 