Seconding language transfer that someone mentioned, I found it to be hands down the best free resource for Greek.

Assimil courses are also some of the best materials out there, I highly highly recommend it if you can find a course for your target language.

As for apps, I use Clozemaster for drilling words (I use a premium account), but you can make your own anki decks for that purpose.

But nothing beats talking to native speakers, either using something like italki for actual lessons, or just finding random native speakers. I often forget words I repeated 1000 times during my studies, but words I learned by speaking to others somehow just get glued to my mind.

Language Transfer is free with no ads or intrusive permissions needed. The material is presented in a way that makes learning the language more natural feeling.

https://www.languagetransfer.org/

For those looking to learn Spanish, find her:

https://youtu.be/G3R4-lj4aaQ

I just had to learn French in middle age, and it’s been fun. They key takeaways from my experience:

1. Contact is everything. The longer you spend listening, reading, speaking, just in general interacting with the target language, the better. Doesn’t matter what you do - Duolingo or PeerTube videos, novels or comic strips.
2. Communication is the goal, not fluency. You can get the gender of a word wrong and people will still understand you. You can use the wrong tense and that’s usually okay. Don’t try to “sound more like a native” or “learn slang words that everyone uses,” because heaven knows nobody is going to take you for a native. But if you can get the point across and can understand what people are saying, you win.
3. Speaking is 10x harder than listening or reading or even writing, because it involves not only forming sentences in an unfamiliar language, but also saying them, which involves your muscles. At first, it’s really hard to say the sounds of the language that don’t exist in your own language, and I found that very frustrating.
4. Language and culture are different, but interconnected. You don’t really speak a language if you don’t understand the culture it’s attached to. For instance, at first I didn’t know what the cashiers were asking me at the checkout, until I learned that they want to see the bags you brought from home to make sure they are empty. The problem with missing cultural references is that everybody around you knows them, and they don’t understand why you don’t, or what there is to explain.
5. One of the very few great use cases of LLMs is, in fact, talking with a chat bot. You give it a good prompt (look for them online) and you are forced to talk in the target language. If the bot can understand you, a native speaker probably will, too. A good tip is to try an AI conversation on the topic of something you are about to do in real life, like applying for an apartment or having a conversation about cheese.
6. Personally, I found that my language skills drowned completely under certain, specific circumstances. For instance, for the life of me I cannot understand voice messages, at all. Even phone conversations are really bad for me, both in talking and listening. I can have a perfectly fine conversation with someone, but when I have to talk with them on the phone, it’s like I never learned the language.
7. The tool you use is not as important as the time you spend. Duolingo was really meh: too much useless vocabulary, not enough grammar and pattern recognition, lack of ability to specify areas of interest, down to always on animations even when you had them all turned off. But, despite the heavy focus on the words, “chouette” and “trousse,” I sort of learned French to the point where I can follow everyone along and can speak and be understood. Took a year to the day and the entire tree.

Im still not great at Spanish because I dont practice frequently but these things helped me:

1. Learned alphabet.
2. Learned examples of conjugation of verbs with real life examples.
3. Started with children level books and increase difficulty to read and comprehend what is being said.
4. Listen to music in that language and learn what its saying.
5. Watching telenovelas with English captions and try familiarizing words
6. Final phase I think is visiting a country who’s primary language is that language.

Study the basics, consume media in said language. Use the language not caring if you do it wrongly. If people correct you, use their input to improve. The trick is getting over the “omg this is embarassing” hinge, when you are butchering it while learning.

The absolute best way is immersion. Full on survival, sink or swim, daily brain exhaustion to cram information in that you will use, over and over.

Short of that, finding ways to practice using the language is the key. Listening to videos is fine, but you need to simulate thinking and responding to make the language part of what your brain goes to. Find people online to talk to via Zoom or discord. I like to think of conservations I have and translate them in Google and re-run the interaction 4 or 5 times in the second language.

For numbers, find videos online that are things like lottery draws.

Bon chance!

need an excuse , time and place to learn one.

Start dating a native speaker of the language :D

But seriously, find a method that works for you. Start by learning common vocabulary, learning grammar rules, and finding a place to practice a language. That could be an instructor, class, online community, or pen pal. There are sites for the latter. Read books and newspapers in your target language and add their subtitles to the films you watch.

Duolingo + language learning Books

I read many great approaches here. One thing that I have the impression it was not mentioned is song lyrics. It’s like syntax and vocabulary get somehow absorbed or something. And it’s fun!

If you are coming from another language, say C or Python, try https://tourofrust.com/

“The book” is always a good option. I like the variaton of Brown University: https://rust-book.cs.brown.edu/title-page.html

(I know that’s not what they meant, I am just preaching the ghospel, here)

See if there are evening classes you can sign up for in your area. This has a couple of benefits over pure self-study: firstly, if you don’t really know any other languages yet, having a teacher to explain new concepts for you will be a big help. Secondly, it keeps you accountable if you need external motivation to keep at something. It can also be a good way to meet new people!

If you’re going with self-study, look up what textbooks people recommend using for self-study for your target language (i.e. not one that relies heavily on having a teacher explain things for you). Obviously a textbook alone is not enough to learn a language, but imo it’s the best way to get to grips with the basics of grammar before you move on to more advanced stages. There are also plenty of online communities to help you out with any questions, especially for more popular languages.

Finally, do NOT expect to make worthwhile progress with Duolingo or apps like that. They are not designed to help you master a language. You might learn some useful vocab from them, but if you’re serious about learning a language, don’t waste your valuable time.

As far as I can tell, nothing beats persistence. Ideally persistence out of necessity, like immersion, although that might be hard to achieve.

It’s not really a thing you can shortcut.

I use flashcard apps such as Anki.