When I started learning Mandarin in 1968, I had flashcards, reel-to-reel tape recorders, and books with no audio at all. I listened to the same comic dialogues over and over until the rhythm and the tones finally started to make sense. If I started today, I would use LingQ, import my own content, and ask AI the grammar questions my old teachers used to answer with diagrams I never understood.
The tools have changed completely, but one habit carried me then and would carry me now: I found my own resources and took the initiative. What is the one resource you could not learn without?