I don’t often see photographers slapping on those horribly yellow gels onto their flashes, and its an elementary mistake, and I suggest, next time you do an indoor shoot with a lot of tungsten (3700K) light around, slap that gel on, also, don’t forget to set your cameras white balance to Tungsten. The Nikon gel to use is the TN-A1. When you shoot without the gel, you adding white light (5500K) to an environment of predominantly yellow light. Most likely your camera is still on auto white balance and sadly your colours will now just be a mix of different colours, not to mention the colour cast you bouncing your flash from. Shooting in RAW obviously helps, but it won’t save you completely. In Lightroom I still nudged the WB to my final taste, but it was not a lot.
Above is a picture with my flash gelled, and bounced to my left to give beautiful soft directional light and accurate colours, reflecting the exact mood of the evening.