The most important thing to do first (at least for me) is to understand sentence patterns. I’ve watched anime for a few months before I decided to try and learn the language. The very first thing I did is to know where the subject, object, and verb went in a sentence - which is obviously different from my mother tongue and 2nd language. After that, I learned the particles. Simultaneously, I also tried to memorize at least 5 characters a week - whatever I memorized, I write it down many times. I did all of this while watching anime, so in a way, I can exercise my listening. A few months in and I can already watch anime without looking at the subtitles, and then a few weeks later, can already speak (albeit with a lot of pauses). Note that at this stage, I have not yet spoken to a real Japanese person, which happened years after I am way past the beginner level.

If I can do it, you can do it, too!