What’s one of the best ways to learn any language? Context! Especially common and relatable contexts.
Well, what’s a more relatable context than taking public transportation in Japan? And when taking public transportation, you’ll hear a lot of announcements. Especially on the train, and especially before arriving at each stop. And no matter what prefecture, city, or line, one can expect to hear「忘れ物をしないよう、ご注意下さい。」 - > “Please take care not to leave anything behind.”
This is a slam dunk for this vocabulary at Level 20 and complements the other remaining sentences.