My strong suggestion - use a standard 18% gray card (one that is truly designed for the purpose) as a white balance reference. White cards can easily be overexposed when using them in a scene as a reference, while the gray card will probably not be either over- or under-exposed. That makes a huge difference when using it as a white balance reference.
Shoot in RAW and include a gray card in one test shot. Then, in the beginning of the RAW conversion process, click on the gray card with the white balance "eyedropper" tool. You will see a Kelvin value that is a result of the calculation. Transfer that number to the rest of the shots taken in the same light and do a batch RAW conversion and voila - you'll have just about the best possible white balance correction.
It is a fact that different light sources have a different color distribution in them. Not all light sources have all the colors in them. Thus, even though you do a white balance correction, all the colors in an image may not be right with some lighting sources. I am planning on doing some research into the different types of lighting sources and the color distribution in them.