What Could Possibly Go Wrong?

I really want to paint clouds. As I was looking today at the sky, I felt that it has a lot more depth than you usually see in paintings. I've been looking around at tutorials, and here is the difference that I'm seeing. Compare these three images: video 1, video 2, video 3. I really prefer videos 1 and 3 to the blue in video 2. In those two paintings, the artist used an underpainting: in 1, it is yellow, and in 3, it is brownish. I think what I might do to test out my ideas about skies is do several paintings. I can try underpaintings of yellow, orange, brown, and purple. All would fade to white at the horizon. That will allow me to figure out what I like. Once I have the sky figured out, then I can do the clouds.