Language

came here to say this. I'm trilingual (native in english, fluent in spanish & italian) and currently learning french. after a few basic lessons on duolingo to get a few words I've found that diving into conversations (I use italki as well as other native/fluent speakers in my network) helps the most and then once I have a basic level of conversational proficiency (e.g. I can introduce myself, say my hobbies, ask for basic directions, order food) then the grammar starts to make sense.

the above video changed how I look at language learning and dispelled the myth that adults need to learn in a different way from children, it's the exact same just the speed and the plasticity of our brains is different.

if I had to learn a language rapidly that wasn't related to any of the ones I currently know (e.g. Greek), I'd do the following

1. duolingo for at least a couple hours a day
2. do not consume any media in my native language, but instead switch to only language lessons (coffee break languages, easy languages on youtube, etc.)
3. once I have a basic proficiency, change the language in my phone to my target lang
4. schedule daily (maybe multiple times a day) italki lessons as well as a language exchange with a native speaker, so I'm using it every single day
5. buy a bilingual book in the language that I already know the context and read it vigorously
6. find a way to use the language locally (e.g. meetups, cultural festivals) and make this at least a monthly habit
7. book a trip to where the target lang is spoken 6mos out

if you do the above for 6mos you'll probably be at least a low intermediate depending upon your discipline. after that I'd then consider switching up my italki lessons to be more focused (e.g. do I need this for work, for familial reasons, what? and then select a tutor based upon that), read more books, consume more content, but continue the habit of speaking, reading, and writing every single day

BONUS - if you have a cultural connection to the language find an excuse for this. while I would've considered myself fluent in italian before my trip last spring, I essentially had to be translator (I was the only fluent italian and fluent english speaker) for a large family dinner with extended family. while it was mentally exhausting being put in a pressure situation really helps your language development because you have to think on your feet, so I now highly value sitautions where you are under pressure, and therefore recommend you find as many opps for those as possible

Godspeed