HMMLORIENTALIA: The tipping point of textual expertise (Adam McCollum). "How much reading do you have to do in a language until you read smoothly, without having to stop often and ask yourself about morphology or syntax, or to consult the dictionary?"
My advice? I adapted this approach from accounts by Cyrus Gordon and C. S. Lewis of how they learned ancient languages and it worked for me. If you're at the intermediate stage of learning a biblical language, such that you know basic grammar and vocabulary, and you want to reach an advanced level, read a biblical chapter in that language every day without fail. When you come to the last chapter, do it again. Don't obsess over detail: have an English translation open at the same time so you can check vocabulary you don't know and get the sense of unfamiliar grammar. (There are also very useful word lists available of rare vocabulary in New Testament Greek and Biblical Hebrew.) Over time you will absorb the language as an actual language in which you can think, not just a puzzle to be solved with a lexicon and a grammar. How much time depends on how seriously you keep to the program, but you will see steady progress over a period months and will feel confident at a fairly advanced level within a year or two. Real mastery takes years.
You can do the same with Classical languages using Loeb editions with facing-page English translations. I find these useful rather than decadent. Read a page every day.
Note well that this approach is only for language learning. Serious exegesis of any ancient text should involve a critical text, lexicons, grammars, and (especially) a concordance.
Cross-file under "Asking the Important Questions."