I made a decision based on incomplete information, and it turned out to be the wrong decision. In carrying out the decision, I caused another human being significant distress, and in the end, my intentions and justifications for my actions don’t matter.
This is no means an exhaustive list of stuff you can try, or even the best or most-proven by research. But I’ve seen and tried a lot of stuff, both in language classrooms and on my own, and these are the things that I always wind up recommending because they worked for me. So, if you’re interested, have a read.
When I tell people I taught myself Korean, I normally get asked two questions: why, and how.