Finally, on the note of color ramps, a common problem is trying to make a ramp by just lowering the value, so you go from say green 240 to 200 to 160 to 120. This is boring and doesn't ramp into other things well. Instead, consider blending in colors, say some reds on highlight to get a yellow-green and some blues in the shadow to make the shift feel cooler. This isn't universal, but it works great if you're doing something in nature, like a jungle that's naturally cooler in the shadows or an Alraune where it makes the ramp to a red or pink flower feel natural. You can immediately see the difference just looking at the ramp.
As an exercise, try a few for different moods or characters. You could even do it with your existing elemental girls: try one ramp for the Calamity Elemental being pissed, with more reds and harsher contrast, and another that goes for a lighter feel when she's on a date with (you). You could pick any girl, but Calamity and Sand will be easier since you only need one ramp.