By studying and being consistent, that's really it.
Once you feel like you've studied enough to be able to understand basic Japanese, you can try "immersing" by consuming native material and from there improve your vocabulary. As long as you keep up and keep trying your Japanese will do nothing but improve.
There aren't any secret or special method, time, effort, consistency are the key. Not only for Japanese, but anything in life.
I try to record myself like I’m shooting a vlog. My grammar is far from fluent but it helps in trying to get the basics down. I often do shadowing by watching japanese vlogs in youtube.
I would suggest listening a lot first. Not just anime or specific media but perhaps a few vlogs or documentaries. Try to hear the patterns in people's speech. Try to imitate it, even though it might be gibberish at first. You can also compare it to the media mentioned, as the intonations and choices of words will shift. As an example, imagine listening to some friends talking vs. a report in the news. In your own language you already notice which words to use and how laidback you can speak. By examining these situations you can learn to gauge how to speak in which situations, so it feels more "fluent" or appropriate.
i am currently learning and it is going well, i am learning via immersion which is basically like when an infant tries to learn a language and they just slowly pick up on it over thousands of hours learning. From what i’ve seen it has proven to be my favorite option and it isn’t that attention intensive either. I recommend the video on how to learn Japanese by Trenton on youtube if you would like to give it a shot!
