nebulous

get a tutor (preferably in person but if you can't; do it online), get a workbook or set of workbooks and work through them with your tutor and do plenty of homework, and be prepared to spend LITERALLY THOUSANDS OF HOURS learning

alternatively move to native country of the language
not sure which route takes more effort tbh

I may be retarded but I’m smart enough not to move to Poland from England.

you still have to study even if you are passively learning via immersion - i know plenty of people that moved to japan and wouldn't have learned via immersion alone

learn macedonian

As a man who knows three languages, it's rather hard to do it. The main idea is to be around the people you learn the language with, but I mostly start from the alphabet and move on to words and sentenses

good way to do it is to start off with duolingo, then once you grasp some basics of grammar and sentences look up a list of the 500-1000 most commonly used words, begin reading books/media after than and look up new words