: You learn five basic sub-skills: edges, spaces, relationships, light/shadow, and the "gestalt" (the whole).
: Many students see a dramatic shift in their ability after just a few specific exercises, like drawing upside down. 3 Beginner Exercises to Try Garantiert Zeichnen Lernen
If you want to dive deeper, you can find the latest edition at major book retailers like Ernster. : You learn five basic sub-skills: edges, spaces,