Turn the white balance either to flash, or manually up to a warm temp, and bounce it off the ceiling or use ttl.
Setting up your camera and flash to commander mode is usually the best since the on camera acts as a fill and the SB-600 is the main light source.
Hitting the subject straight on from the shoe is also good if there is enough ambient light and you're not at a high aperture and 1/250 sec.
For more ambient and less flash in the shot lengthen the exposure time.