I experimentally tried to paint it with only white blue red and yellow since theoretically you can make anything from that. I think next time I'll just let myself use the burnt-sienna. I would usually make black-ish with some burnt-sienna and blue and I found it took a lot longer without that. There is a little bit of "sparkle" on the pony's mane. I dabbed some iridescent white on it. I bought that iridescent white thinking "iridescent" just meant it would be extra super white, didn't realize I was literally buying a tube of glitter So I'm always on the lookout for something legitimate to do with it.
I like this pony toy for values study because it's mostly white. Unfortunately that brilliant purple was also not really something I could get across with my red-blue-yellow-white. I know there are tricks you can use to make a color look more color-y by juxtaposing it with its complement. I'm not experienced enough to make that happen yet but I will keep at it.
Inadvisable color choices aside I meant this mostly as a practice of values and form and I think I did pretty well on both of those so I'm happy. It's only my 6th painting ever on a "proper" surface (in this case canvas board 12x10in).
Preliminary studies: form, values (also featuring "how do I cube? dangit" *quickly googles perspective tutorial*)