Hi I don't play ranked and am also not the best Jhin main but I still somehow manage to win most games. I am also not on any EU servers and don't know any Jhin one tricks from them so I can't recommend anyone that can show you personally. I can ask around my club though.
First of all, runes.
Personally, I run Hail of Blades with Taste of Blood, Eyeball Collection, and Ravenous Hunter + Biscuit Delivery and Cosmic Insight from the Inspiration tree. Some people may take Fleet Footwork instead of HoB, but you do you.
Second, build.
I got this build from a suggestion made by one of the people in the club I'm in and I've found it works well, but you may want to switch up the build order depending on the circumstances.
Start
and a potion, as you do.
Build
.
Build
.
Finish
.
Build
.
Build
.
I have several items I build last, but recently I found out that
still works on Jhin to some extent. The people I hang with recommend building it last if you do decide to build it. Other items I have as options are
,
,
, and
.
In terms of boots, I don't always build
. It just depends on the circumstances, really.
Third, technique.
At the start of the game, when the minions first reach lane, there should be at least three that become low health quickly. Wait for the enemy minions to poke those three minions down then pop your Q on the lowest heath one. If done right, you should get all 3 minions.
That being said, your Q and your E are good for farming and keeping your enemy at a distance. I, personally, throw my E to the minions at the back of the wave. This gets those minions low, and if your enemies are low, it may aid in slowing their retreat and possibly kill them. When using your Q, only use it on low health minions to avoid wasting mana. Late game, both these abilities can make quick work of large minion waves.
If you're feeling risky, you can also flash Q or flash fourth shot a low health enemy under turret. If you don't want to risk it though, a well placed W should take care of them.
Your ult is not meant to be rapidly fired off. Slow down, breath, and observe. If you fire and you see you're enemy is running from side to side, try to plan their movements. If they are running in a straight line, they deserve to die. Your ult is also good engage and back up for teamfights and ganks, and can also be used to pick off any enemies that may have gotten away. You can also use it to steal drakes, Baron, and possibly Rift Harold(I have never stolen Rift so I'm not sure).
Forth, the team.
I have found that Jhin works best with supports with hooks an roots, as you can combo them with your W.
,
,
,
,
,
, ect are all good picks for Jhin.
Enemy ADCs I personally don't like while playing Jhin are Xayah and Kai'Sa.
Other things to be aware of are your vision score, map awareness, and teammates. If the jungle and/or river are dark, you're in danger of an ambush and need to ward up.
You also have to pay attention to what's going on around you. If you've got the enemy bot lane under turret, keep an eye on the map. If you see the enemy jungler coming down the river, ping for danger and back up. If your support stays(which mine often do), leave them as its not worth you both dying. If they bitch, say you warned them to back up. Also, keep an eye out for enemies teleporting in behind your team. If you see it, danger ping it. This may also be a "no shit" thing, but pay attention to your enemy laners. If they aren't there, MIA ping.
Also, pay attention to your teammates. If you see them making the same mistakes, try to help them out. If they don't listen, that's on them, not you.
Not sure how well this applies to ranked, but I hope it helps regardless.