How do you actually improve at LoL?

Lately I've been feeling as if I have hit my ceiling. I play ADC (played it ever since i joined this game) and Jungle (although jungle is just this season) and so far I've done about 108 games and i climbed from Silver V to Silver II.

But it feels not because i was the reason. In fact, I'd say that when I win, i have someone with me that did well. My recent game, Sion (top) had his struggles but was our main engage and tank. He had clutch ults, he took charge and all i did was follow up properly.

I had a score of 8/4/12 as Gragas Jungle. Yet my early game SUCKED. For some reason, I can never get this massive gank streak going that I see main junglers do.

I get the concept of GANKING: You gank when the opponent is overextended, your laner has enough health and resources to help you out, when you know the brush is not warded or when you KNOW the enemy jungler is going to gank this lane. I also know when to counterjungle. Which is when you see the enemy jungler on the map and go on the opposite side and take his camps. I know that I should cover lanes so i can get free xp. I know that when i get a gank of, i should push the turret for pressure.

I know the things i should be doing yet, i could never set up a gank. It was too difficult. Sion overextended plenty of times. the enemy lux had always had her brushes warded and the same goes for bottom. Maybe those are excuses or maybe they are valid reasons as to why I couldn't gank. The point is, I just couldn't see a way to gank.

The only reason WHY we won is because we took more objectives than they did. My impact as a jungler is always too low. I have to essentially pray to the gods that my laners don't feed before I can be effective.

It's such a struggle to do well in the early game as a jungler and no matter how many replays i watch of myself, i can't figure out how to implement what i know abuot ganking and use that IN GAME.

THAT covers jungle.

My biggest disappointment is my performance as an ADC. I've been playing Lucian since Season 4. Yet, i can still have games where I just can't win a game. It's incredibly hard for me to kite, to even click on the targets while i'm moving around.

Again, I know almost everything there is to know about how to play ADC. I've seen lectures, guides and all that. I understand what I need to do yet I can still make those fundamental mistakes.

People constantely say that you should improve but my question is: how do you actually take what you are doing wrong and fix it? Watching replays only shows me what I already know but to me, kiting and clicking on what i want to click on is incredibly hard to do.

So how do I get better at ganking, kiting and clicking on the right targets? And so many more things that I find not so great about my gameplay?