Learn Biblical Greek by actually using it
Koine was the everyday Greek of the first-century Mediterranean, which is why the New Testament is written in it, and why it's simpler than the classical Greek of Plato. Most courses teach it as pure decoding: parse the form, look up the word, move on. But producing the language yourself, even a little, out loud, is what makes the forms stick.
The vocabulary is kinder than it looks too. A few hundred of the most frequent words cover most of the New Testament text, so reading real scripture in the original comes surprisingly early. Parlita has you using Koine actively from the first session, with corrections in context and spaced repetition built from the words you actually met.
Around three hundred words cover most of the New Testament, which makes Koine the most reachable language on this page. A few months of steady vocabulary and you are reading real verses rather than textbook exercises. The alphabet takes a few days. The accents you can largely leave alone at the start, whatever your grammar implies.
Participles are where it turns hard. Greek uses them constantly and stacks them in ways English simply does not, so one verse can hang four clauses off a single main verb. The middle voice is the other one, a category English lacks entirely, where the subject acts on or for itself. Neither is learnable from a chart. Producing the forms yourself is what makes them stop being puzzles you solve and start being things you read.