The 'Full Course' Tutorials by Learnit (YouTube)
youtu.beWhen you need a deep dive or want to look up a specific basic feature (like the Shape Builder Tool, Pathfinder, or working with layers), Learnit's free, hours-long courses are fantastically structured with clear chapters.
What you learn: Customizing the interface for a professional design workflow, the difference between vector and bitmap, selection techniques, color swatch management, and transformations.
Reminds you that working in Illustrator requires a shift from "pixel-thinking" (like in Photoshop) to "formula-thinking" (vectors).