It depends on the language, but generally, use anki decks, study grammar (you can often find free grammar resources online) and read/watch/listen to content in the target language. Having a course for the basics helps but often good options heavily depend on the language
Eventually, you can start trying to communicate with other speakers, either online (via text chats/voice chats) or IRL if that’s possible
People still use DuoLingo? Why not learn a language properly?
What free online courses would you suggest? Honest question
It depends on the language, but generally, use anki decks, study grammar (you can often find free grammar resources online) and read/watch/listen to content in the target language. Having a course for the basics helps but often good options heavily depend on the language
Eventually, you can start trying to communicate with other speakers, either online (via text chats/voice chats) or IRL if that’s possible