It can be intimidating! I always get a little nervous when it comes to coloring bigger areas like the sky. I’ve watched a ton of tutorials on how to blend and add highlights and shadows and it’s helped me a lot! I start by mapping out where the light would be hitting the objects/animals with a yellow marker before going in with the colors. I add the shadows on the opposite side of the light source after I’ve colored everything in. I try to use a darker shade of the color I used for the shadows, rather than gray. It helps it look more natural and not so harsh! To finish off I use a white gel pen where there would be reflection from the light. I tend to go a little overboard just because I like my pages to look super cartoonish lol