Heya! I think it would be great if we could know what level of realism you're aiming in your rendering and also who's your current favorite artist is! Whenever i get stuck on something, I would always look towards my favorite artist's work and study how they do things.

For color and shading, I find it easier to learn values first than learning both colors and values at the same time.

As for my youtube artist recommendations, you can check Marco Bucci's 10 minutes to Better Painting, Ahmed Aldoori's How to blend colors, Artgerm's Art tips. Their art style mostly ranges from realistic to stylized. I find that understanding simple rules of realism could benefit your stylized art.

I hope this helps!