I mainly work with digital art (not ai art), but I do still have experience with ink, watercolors, gouache, and acrylics.

I had to learn everything on my own -- colour, composition, values, shape theory, silhouetting, etc -- as my school rarely offered art lessons. I strongly feel that the best way to approach art and illustration for newer artists involves both rewarding your interests in illustration, as well as gradually familiarizing yourself with the main principles.

In the past, I'd also had experience as an origami tutor for a couple of years, and my lessons resembled a structure like so:

Introductions & understanding everyone's goals and preferences --> basics, some freestyle working just to see where everyone is at --> and then gradually increasing the difficulty as more principles and concepts get introduced.

For the more difficult lessons, I think it might potentially be fun to start in this order:

Textures defining of different art styles and periods (pointillism, hatching, cross-hatching, blending tools, etc.) --> composition ratios and guidelines --> values and working with contrast in monochromatic settings --> colour theory and experimentation --> shape theory --> anatomy and simplification of anatomy --> perspective. Though I do believe that lessons should be tailored to the needs of those you're assisting.

This structure was one that I used on myself when I first started genuinely wanting to learn and improve, but I do think it's also good to reward your own interests with fun, indulgent drawing.

Too many people get stuck with the smaller details, and they forget to enjoy the bigger picture.