Welp. Back to the kitchen for sandwiches. Jk.
Git gud. Not by asking God for skill, but by committing some time to research. It's not like everyone got pro by accident. Playing the game is always a start, but thinking about it helps just as well. Of course there's a healthy balance in committing time to a videogame, but you know: Don't just look at pro-streams in awe, try to understand. Sounds pretty old, I know, but that's how I got gud (relatively :| ).
Finding mistakes in your own plays is important. Of course you can find mistakes in every situation, but limit yourself to the important ones first.
Cover these areas: Mechanical Skill, Decisionmaking, Teamplay (teamplay defined as "thinking about what your teaam might do and adapting")
At best, you only watch pro-streams that explain something (if you watch them at all). Scarra is a pretty fun dude, and he summarizes his thoughts during the game. Look it up on YT.
Actually do the math. The formulas aren't that hard, and once you understood how stuff is calculated, you can judge situatons somewhat accurately and actually try to theory-craft on your own (if you don't want to be a meta-sheep/understand why stuff is meta)
Final word: It's all about abusing advantages. That transfers to decisionmaking, matchups, items, cooldowns, vision...
Hope that helps.