I'm also not a great concept artist but maybe I can help.
1. Right now it looks like your color scheme is one area you could easily improve. Your shadows are currently just darker value versions of your base color. And you have a lot of black in your shadows. This is causing it to feel washed out and dead.
Your shadows should be the complementary color of your light source as you get darker (yellow light = purplish shadows, red light = greenish shadows). I find I like the results I get when I move away from my base color toward the complementary color as I get to darker and darker areas.
2. I would suggest a unified color scheme for the entire creature or even painting. Right now your hair looks great but since the body doesn't have the same color scheme it looks disconnected. I did some paintovers with what I thought were better colors but I still wasn't too happy with the results until I started pulling colors from the hair itself. Then it started to feel much more unified.
Here's an example of colors I pulled directly from your hair. And below that an example of my and your schemes side by side so you can see how much more integrated having a unified color scheme feels.
* my color scheme is laid out on the left and yours is laid out on the right
After sampling the colors from the hair I simply painted over a greyscale version of your lion.
If you check the Color Picker and use the eyedrop tool you can see how much more saturated my shadows and those of your hair are than the shadows you are now using on the body and face.