For those who believe in negative energies, any color will do. It's about your own mindset, your own belief. If you feel pink or cobalt blue or green or red is what you need, then go for it. There simply isn't one right way to do it.

I don't believe in negative energies or spirits or whatever. But I've had friends whose belief systems include such things and while white was probably the most common, other colors of "protection" were also used. It was very individual.

Point is, go with what works for you.