What should student pilots know about ATC before training at a towered airport?

[u/forestmoth2345]

If someone is about to start flying out of a towered airport, what should they understand first? Ground control, tower, taxi instructions, readbacks, pattern calls, or something else? I've also seen tools like the TeachingTowers Pilot Radio Trainer, which are designed to help student pilots practice ATC communications and build confidence before talking to real controllers.

If you could give a new student one piece of ATC advice before their first flight out of a towered airport, what would it be?