In really brightly-lighted places at night, do not be afraid to stop the lens down to f/11 or even f/16, which will usually produce nice diffraction stars on point light sources, like street lights.
White balance bracketing can be one thing to try: see if you prefer the scene rendered with Daylight or Tungsten WB, or a manually-set WB. Actually setting a white balance can have a different effect than letting it just run wild in AUTO...the camera is going to try and process the information from the color matrix based upon "some type" of white balance point...so...SET one, do not just let it yo-yo in AUTO.
In AUTO-exposure modes at night, allowing the camera to "time-out" the needed amount of exposure, it is often necessary to set the auto-Exposure Compensation to the Minus side, so as to keep things looking like a nocturne, and not some odd, abandoned city during a dust storm at noon...
Oh, and if you want to do light painting...wear dark pants and a dark hoodie!!!!