There is not a one-size-fits all answer to this but generally speaking.
Any method/environment that gives you lots of comprehensible input (language that you can grasp the meaning of) and is just a little above your current level.
Secondly you will need some kind of ‘feedback loop’ in that when you try to use the language or guess at the meaning of difference phrases you will get some sort of response, i.e. you can not learn language in a vacuum.
Finally it should be enjoyable for you, when you are stressed it will stop you from absorbing language (see: the affective filter) and it will also cause you to refrain from practicing/learning again. A certain level of stress or confusion is normal, but too much can be fatal.
If you would like to hear more about language learning, particularly self-study you can follow Lingo Steve on Youtube, he is an educated, experienced professional language instructor with a lot of common sense advice for language learners.
Alternatively I have written a few short articles on the matter and you are free to send me any queries but I would definitely recommend you check out Steve's work first!
Good luck with your language journey and my final advice is “intensity is always the best way to start” start with an intensive experience that won’t leave you in shock but will instead leave you knowing that you too have an ability to succeed in a foreign language.