Hey! Well, if you intended to paint the character with the sun behind them, then that’s where the main issue comes from. If the sun is in the background, then most of the character, at least the parts we see, would remain in shadow, since the sunlight wouldn’t be hitting them directly. Only some edges of the silhouette would catch light, creating more of a rim light effect. Also, the sky should have warmer orange sunset tones, while the sun itself would appear as a desaturated yellow, almost close to white. Always remember to use references when painting Now, if the background is very warm, then ideally the character should lean toward cooler tones. That way, you create a stronger warm vs. cool contrast and avoid having everything covered in warm colors, which can make the image feel muddy. Hope this helps!
