There are lots of great things to do, but most important is to build a habit and keep working at it. Engage with the language every day, and work up to consuming content designed for native speakers.

Duolingo and similar apps are helpful, but don’t put all your eggs in that, or any single, basket. Also do Anki or some other flashcard thing. And at the very least a beginner textbook or grammar guide is good to have. Early on, mix time between textbook, apps, ‘comprehensible input’ videos. Work your way up to reading, and look for graded readers to get started.

(Also, as Duolingo gets worse, consider alternatives like Memrise and Mondly. Or even paid stuff like Busuu, Lingq, Pimsleur, Babbel, Rosetta Stone. Also, your local library may give access to Transparent Language or Mango. Although of course I can’t vouch for most of these personally.)

Another rec: check out !languagelearning@sopuli.xyz for a cool community. Good place to ask questions and get support.

There are probably a ton of cool learning resources specific to your target language. Look online for communities around it.