Best way to improve in LOL?

What I have found insanely helpful, and what lead me climbing from silver elo to high plat and even diamond is watching coaching streams, you should look up LS on youtube, this guy has really great videos, where he talks about simply the fundamentals of the game and their importance, then going more in depth when coaching Higher Elo players concerning micro and macro play. And, honestly, a really cliche thing to say, but just play more, there isn't a single competitive game where you are the best when you start to play, you gradually improve, learning different concepts of the game as you play.