An underpainting is definitely a part of the beginning of creating a painting. However, it’s not the very beginning. If you’d like to begin all your painting with confidence instead of confusion, check out the “How to begin?” course
I paint from a photograph and you’ll see how I go about creating an underpainting. I use just 2 colors of paint. Well, actually 3 because if you notice, my canvas is a color. It’s not white.
An underpainting is something you should definitely consider using and learning about as it will make the process of painting so much easier for you when you understand how to use them.