The best course of action is to consume as much content in the target language as possible, tv shows, music, YouTube videos… Your brain will eventually pick up on certain parts of the language naturally. Also the best thing you can do is to not force yourself to speak or write in that language until you are comfortable doing so (this is one of the biggest things doulingo does wrong).

I can attest to this method working as I went from barely knowing a couple of English words to speaking it in about 4 months (you could probably do less if you stick to what I outlined above). To back up this method I suggest you look at antimoon which is written by people who have used this to learn English as well.