lol-coaching.com is a great resource to get free coaching for whatever role you play. I'm definitely willing to help you if I can, though I don't claim to be a great player. I recommend you download a replay program like SkinSpotlights Replay or LolReplay and watch replays of your ranked games. This really helped me identify my own mistakes. This also allows you to send replays to other people with the same program so they can help you identify mistakes you make.
Looking at your stats on op.gg:
- Your CS per minute is very low. You very rarely break 5 CS per minute. I would recommend going into custom games and just practicing last hitting.
- Your damage to champions is less than I expect for the champions you play. Even when you stomp a game you pretty much never lead your team in damage to champions. Why this is happening is very hard to tell without watching your replays but it is most often caused by being out of position in team fights so that you either die too soon or have to spend most of the fight fleeing rather than dealing damage.
- Your KDA, while not horrible, is not great either. You should be looking to achieve an average KDA of >3. Furthermore, your KDA game to game swings widely. You have many games where your KDA is very low and then a few games where your KDA is extremely high. The root cause for this is also difficult to assess but it is most commonly caused by not understanding when you have an advantage and not properly warding. Try to keep a closer eye on the minimap, don't chase for kills into areas where you don't have wards, and never try to solo an opponent that you don't have a gold and level advantage against.
Like I said, I'm willing to help if I can. Hit me up sometime or if our schedules aren't matching up you can check out some of my games on my youtube channel. I try to play a wide range of champions and explain my logic and reasoning during games.
https://www.youtube.com/channel/UC2EZm50wNGmfJal7IHM_b8Q