Ways im improve?

I'm not the best at the game never will be. I'm a very strong laner and generally I make smart decisions. I'm aware of most my own flaws like I play "not to lose" I am bad at following up on roams. I am very smart when it comes to itemization. I'm not the best mechanically hence I focus on playing mechanical simple champs and use my game knowledge. I end up getting frustrated and autopilot. I don't seem to be having the correct approach how can I win more games. Would like to add i've played 4+seasons I prioritize fun but my winrates as bad as season 4 how can you get worse? Do you have any tips?