Whiter than white
I always used to struggle with painting white as it can come out like a piece of paper with no gradation in it or you get the high contrast approach where figures look as if they are in Daz white clothing under a dazzling sun. One obvious rule is don't start with white because once you start with white there is no place to go with highlighting White is the top of the highlighting tree.
I have tried starting with white and using washes to darken but for me this often ends badly with dirty streaky white and then having to airbrush in a smoother white to highlight again. I have also tried starting with grey and airbrushing up to white which is better but tends to produce a very uniform white. This is fine for doing 50 space marine shoulder pads but less good when you need a bone white or an off white.
Imagine my delight then at being asked to paint the Gandalf and Pippin mins from GW. These are great miniatures - the best range GW have ever made in my opinion (apart from the finecast rubbish) however Gandalf is now Gandalf the white on his white horse Shadowfax. Lots of White.
Fortunately I had recently learned how to do whites from the master - Angel Giraldez on you tube and this video nails it.
In the video he starts with German field grey as the base coat and then highlights with German camo beige and tops off with deck tan - all vallejo model colours thinned for the airbrush. I would never have thought of this as i lack an artists eye for colours but the "white" produced has depth, shade and best of all can be a base for changing or lightening the white. In my version of Gandalf and Shadowfax i added a more off white linen type colour to the cloak and a more pure white to Shadowfax to provide contrasting whites. For his hair i highlighted with an off white.
The staff again was sprayed in the same manner but then had a bit of blue white magic power colour added. Lastly I added a bunch of white flowers on the base in case it wasnt 100% clear he was in white.
I cant recommend the Angel Giraldez videos highly enough for learning new techniques.