Hi, I'm new to pixel art, and I'm having a lot of trouble creating of a palette, specifically AAing with a limited one. I've looked up everywhere and read various threads, but didn't find much... (besides, lots of resources are dead)

For instance, this person uses blue/green as a medium tone between the greys, and even though it adds two more colors to the palette, they can be used for other things too besides blending:


That is what I want to achieve. I've read that the colors need to have the same "temperature" but I don't know how to do that. I tried turning the palette to grayscale, and thought that colors of the same value would work together, but that doesn't always happen. Can somebody help me?