Exposure and immersion is really key. Things like taking weekly lessons are a good start to get your basics down, but once you know those basics and you can understand a simple “Hello/How are you/What did you do last weekend?” conversation, you know enough to start reading children’s books, watching simpler TV shows, etc. I’ve tried learning Polish and French for ages, it wasn’t until I had media in both that I liked that allowed me to have constant daily exposure that my language improved.

My two secret weapons were reality TV and YouTubers. It exposes you a lot more to casual speech, and accents/dictation that are more varied than what you get in most educational material or scripted TV. Also easier to find specific dialects, like Quebecois French, which can make a big difference (learning France French is a good start for understanding Quebec French, but you’ll be completely unprepared if you’ve learned on nice, clean, Parisian accented French, and then try to listen to someone with a thick Montreal accent). News is also a good thing to watch or read, especially reading international news so that you can see reporting on events you’re already familiar with.

Things like Duolingo are basically useless beyond simple vocabulary development. The phrasing they use is often unnatural, and their automatically generated content isn’t reviewed for grammatical correctness. Flash cards are way better, but depends heavily on whether those are good sources of learning for you (I find them generally useless, I struggle with ADHD too much). Podcasts can be okay, but you have to really be far into a language before just listening to someone speak continuously with no visual cues is comfortable for you.