Hey, I will talk about colors only since it's your note for muddy colors I think you shall tint more your shadows and not try to use grey/black on multiply layer. You can try some fun things with a gradient map, with the light part full white, at maybe 80% of the gradient a lil bright color like orange and a light purple for the shadow and put it on multiply effect. ( tint more the lights too, without burning it white everywhere) Try to have fun with vibrancy too. Don't forget to check values, u did great job on the first plan, i pretty enjoy your rendering on the bottom dress. Hope it helps ! :)