This looks very good

Hey there! You received some really good feedback on what you can do if you decide to paint using only one layer. I don't have much to add to that. What I would like to correct, though, are the values in your scene. Even if you're painting on a single layer, keep values and lighting in mind. The scene looks flat because the character doesn't stand out; there's no difference between the character's values and those of the rest of the scene. If the light source is behind the character, they should remain in shadow, with only the edges illuminated. This will make the character stand out immediately and create a stronger visual impact. :) Hope this helps!

When painting on a single layer, general rule of thumb is that you block out your midtone colors, add your shadows, and then add your highlights. This way, you don't have to worry about muddying your lightest colors and you have a base to put the darkest tones on and also somethin to blend them with if you choose to. I think the piece could really be improved by painting over some of the places where shadow should be in order to give more contrast and also a sharper edge to things like cast shadows. I can try and do a paint over later.