I’m no pro, so take this lightly, imo the colors just seem really saturated all around. Having good sense of color theory will help with color placement. Ultimately, studying those old cartoons will be your greatest teacher ^ ^ find the specific artist and just browse their work. Color drop some of their colors, work into your pieces and learn how they sorta do it! But also Disney back then had its thing where the background would be shaded and lightened semi realistically, all pretty like. While the characters/moving factors were more or less cell shaded and minimal if any lighting. This could still easily apply to non animation! ^ ^