Gamerchik, I just want to double check. Do you want like a platinum blond hair colour or a really pale yellow? Being pale as the moon would say grays but you mentioned using yellow.
Reason I'm asking if if you want to achieve a really desaturated yellow, try experimenting on some scrap paper with the following idea:
Lay out the different yellows you have and any purples you have. Try mixing each type together with a ratio around 3/4 yellow and 1/4 purple. Lesson and increase the amount of purple to see the gradients of what you can expect and finally slip in some skull white to brighten it up. You'll no doubt find that different yellows and purples work in strange ways with one another but if you try this, you may find the look you are going for.
Reason why? Purple is yellows complimentary, while they look good side by side, if you mix them together they cancel one another out. wink