Learning a new language takes lots of time and practice. Immersing yourself into the brand-new language as much as possible is the best way to acquire new words, phrases, and grammar.
Immersion can be physical, such as living in a country where your target language is primarily spoken, but this does not have to be the case. Watching videos, listening to music, reading books all in the language you are learning all count as immersion.
I do this daily with Esperanto. Since there is no one place where everyone speaks this language the next best thing is the internet. When reading, I just read. Not looking up every word but instead listening to what my brain is "saying." This allows for grammar to get ingrained and has helped me a lot with the apps that follow.
Also when watching videos or listening to music, I am not trying to understand what is being said 100%. Most of the time I still have no idea what is being talked about, but I can tell there are improvements.
What I like about videos the most is being able to see a person's body language while they are speaking Esperanto. This adds context that audio lacks and helps my brain to store information about these new words to help create links while studying with apps and grammar books.