how to get good

Play consistently and play proactively. It's hard to be good a league when you are not thinking with purpose. If you autopilot in league you're not gonna get very far unless you're a prodigy or some shit.

I think a real important part of learning league and getting better is learning wave management (if you are a laner)
If you are support learning where to ward and when to roam is good
If you are a jungler learning proper jungle clears and decision making in the early game is important.

Focus on macro and objectives rather than trying to go 30/0, because once you're in late game you can be 30/0 but if you die once, the other team will finish the game

play with friends and practise

the game's mostly just genetics, nothing u can do bout it buddy boyo, especially if ur left handed

quit league of legends and get girlfriend,friends,touch grass, go to gym

stick to one role and master it, also check tierlist and pick best champ in current meta

learn champs power spikes, farm, vision, and map control

learn champs spikes and situations