As a qualified, practising teacher of English as a foreign language, I guess I should be able to help. For competence, once you've got past the basics of grammar, it's mostly about memory. Create a database of words, phrases, and example sentences, and use some kind of Spaced Repetition System (e.g. Anki ) to keep reviewing them. Fluency is harder. First, what does it mean to be fluent? Last time you were in a shop a…
It's nice to hear this from a professional. I am an English speaker who speaks a couple foreign languages. When I am alone in my car, I talk to myself in foreign languages or have mock conversations. I repeat them over and over again. Then in a real conversation, I mix and match large phrases from my vault of mock conversations rather than translate word for word.
(Yes, "tape" is a colloquialism - I realize they probably use solid state media.)