Hi, for my part :
<ul><li>
Music doesn't work. It helped me with the language sounds while learning English as a child, it hasn't helped me much since. I'm a huge opera fan, it didn't help me with Italian at all. Exceptions : Karaoke which requires a big effort. A friend of mine also recorded herself speaking / singing, and basically listen to herself, apparently it's tremendously efficient. Movies : use original subtitles to really learn.</li><li>Translations : While it's a very good general exercise to learn to know the intricacies of a language better (your mother tongue's too!), I didn't find it really useful for learning (but maybe I just lost the habit and I should give it a new chance).</li><li>
Reading texts about subjects of interest to me like news articles, with a good dictionary next to me (or !wiktfr on DuckDuckgo, Livio apps on my phone which are based on wiktionary). Etymology helps me learn.</li><li>I use RSS feeds to collect articles. I try to
read them entirely once before using a dictionary. Books when I'm motivated. Be
selective about your news sources as badly written content is well spread even on major websites.</li><li>Flym, bypass-paywalls; Kiwi browser with extensions, 'nuff said</li><li>self-built
vocabulary lists, reviewed
at least once a week using your preferred learning method. The Livio apps bookmark feature is good enough for me there, but you can make your own Anki Decks/cards/notebook.</li><li>News and podcasts : German podcasts and news (I'm fluent) and Italian news (I'm rather a beginner) every day, at least for the language music.</li><li>A good grammar reference</li><li>A good learning book / formal writing guide</li><li>Mezzofanti Guild linux mpv youtube-dl tricks.</li><li>Nemanja Nedeljković's uniread </li></ul>
<ul><li>
Writing business stuff, business conversations : the best imo. I regularly feel like I'm starting from 0 all over again, because I have to channel my (non-language and language) competences for a purpose while directly confronting another culture. Formal,concise email and reports, purpose-oriented conversations...</li></ul>