A long-time English learner here. I'd say variety is your friend. I don't know any learner who has mastered a language by sticking to a single technique. You w

A long-time English learner here. I'd say variety is your friend. I don't know any learner who has mastered a language by sticking to a single technique. You would do everything, maybe with varying levels of comittment - read textbooks, take classes, do flashcards, do speech shadowing, talk to native speakers, watch movies and TV programs, etc. After becoming able to say what I want (more or less), participating online discussions in the topics I care has been useful for me. It taught me how to structure longer chunks of text to express more complex ideas - you would be surprised to see how often sentence-to-sentence translation fails (between Japanese and English, at least). If you are starting as an adult, native-level pronunciation would be difficult to achieve, even if you invest decades into it. I have almost given up on that front, and instead am focussing on how I can make my pronunciation less misunderstood. Part of that is to pay attention to vowels and consonants I'm not good at (or to use easier-to-pronounce synonyms where possible).