This blogpost, coming from this twitter thread, can help you with choosing color palettes in Midjourney.
Also, check out this blogpost for more on colors: https://stefvanlooveren.me/blog/mastering-color-techniques-midjourney-v5-example-prompts
Cobalt Blue, Scarlet, Pearl White 



Coral Pink, Turquoise, Cream 



Maroon, Gold, Black 



Turquoise, White, Brown 



Royal Blue, Gold, Ivory 



White theme 



Gold theme 



Soft Pastel Palette 



Duotone Palette 


