if the scene is artificially lit, check if the light temperature is below the nominal 5500K (yellowish light) or above (cold cathodes, tungsten lights, bluish light). the best way to do it is shoot a white blank paper with the daylight WB setting and see which way the paper's hue turns in the light. (hold the paper so that the place's lights shine on the sheet.) if you have below-5500K lights, use one of the yellow or orange flashgun filters. if above, use blue or green filters (depending on the hue of the lights). and if you want to have true-to-life colors, use a grey or a white card, and use the preset WB function with them.