Critiques and advices pls

[topaz agate]

i feel like something is off but idk what, can someone point it out and give me some solutions to fix it please? That'd be appriciated

[indigo cairn]

Instead of using black to shade (as it makes the skin look ashy) try a darker shade of purple for the red of the skin plus the blue hue of the background. Hope this helps 🤭 ✨