Passive Tips and Know How
There's a TON of math on how attack speed and Crit chance increase Jhin's damage value, but honestly the biggest factor is your level. Stick to the listed items and you don't have to even think about it.

Having a set attack speed means slow attacks. Weave in Q between attacks and W while reloading (Only If You Don't Have To Move!!!) to keep damage steady.

The Fourth Shot™ is pretty strong. You absolutely CAN flash in to turret to kill the adc at level 3 (if below 300 health or so might need a q too). Use it to poke and chase. TFS™ > W > Q > AA is great for this (best with Rapidfire cannon). Never ever shoot your last shot when someone can jump on you in a teamfight. It seems tempting but you are now dead for 30 seconds and now you must watch other people play without you.

Q Tips (haha)

aa>Q>aa is a nice opening to any fight and even aa>q is good poke. Be careful not to cancel your auto attack though. If you find yourself doing so, just q>aa

I keep hearing about some magical damage you get from killing 3 minions with q and having the last one land on a champion. This is inconsistent at best and borderline impossible to set up on a regular basis. It is a cool few hundred damage though -if- it happens.

For later minion clearing I Q a caster and shoot him before it bounces to another caster to get the extra damage to bonk them instantly.

For fun I always try to get the three starting melee minions with one q.

W Usage

Follow up every time someone is rooted. At best it lands to a kill at worst is prevents them from retaliating on your teamates. Don't be afraid to blast this when you're reloading in a fight for extra damage. DO be afraid to blast this on minions but sometimes you NEED that cannon before you go back.

E usage

Mostly put this is a bush to slow JG and lightly zone their sup.

Can be used to throw on teamfights mostly for the slow that helps your team instead of damage. Can also be thrown when you're being chased to slow them down

I've tried using it to place under tower to wound a crashing minion wave but it usually doesn't help enough. It does help dissuade tower dives though.

Ult Usage

Sniping someone far away is difficult, your first shot is the most likely to hit and feel free to take a second to make sure that last shot hits something.

Best used on fleeing enemies, enemies in team-fights, or just to cover a teammate who's running away.

Also because it does more damage to low health enemies, this is a surprisingly useful tool to snipe dragons or barons (mostly dragons). Try to position yourself where you shoot through the epic monster and still hit someone.

Autos

Jhin has a longer wind up time to shoot therefore it's very easy to cancel an auto compared to other ADCs so be warned.

Because every shot matters I have "target champions" on quick cast so I don't accidentally shoot minions/wards as often in fights.

Galeforce
Use this to snag a kill or run away, but just make sure you use it. Can also be used to proc dark harvest because of the multiple hits and synergies well with it.

There are some problems
I freckin HATE the new mythics with Jhin. Galeforce is currently the only option as eclipse is too weak on ranged people but even that wasn't very fun.
Ideally I'd like to build StormRazer and Rapidfire cannon every game as my first items but mythics are too powerful to ignore or even delay and really limit the build options.

Barring a total item overhaul, I'd like to see some minor buffs to Jhin's attack range so that I don't have walk into a danger zone every time I don't have RapidFire Cannon. The Q could also use some love; I'd like to make it more effective against champions. Maybe "if the first 3 targets die, the fourth one crits"? Or even just "last bounce prioritizes champions" to make it more consistent.

Things I Like
His kit is very fun to play and use as also he looks nice.

We live in a society
As it stands Jhin is too fragile to solo carry and cannot survive on his own. If I solo-que I just make it to 30 minutes, where I then lose because I get jumped. I could be 19/3 and just get merked by amumu+someone-else and get taken out of the game.

I cannot make any plays because to leave safety means death at all hours. Without cordination and a plan, you will get punished so hard for being in the wrong spot at the wrong time. At no point will you be strong enough to confidently kill both the ADC and support, whoever they are, alone.

YOU NEED FRIENDS TO WIN AS JHIN
Without a duo as Jhin ADC you will find yourself struggling more than most other ADCs would, and far more than anyone who IS in a duo. I would not recommend Jhin solo que if you want to climb or even just win games. You can consistently win games however, with friends. Jhin can compliment or spring board off of many types of champions, play-styles, and specific abilities. jhin's are very useful to a team that needs a high damage dealing man who can secure kills and lock down fleeing targets.

Current Meta
Pretty decent and consistant

Skins in order of cool
DarkStar -
cool everything but sometimes feels like slower animations
Project -
man/machine cool look nice sounds for animations
Everything else-
Meh
Bloodmoon -
bad shooting noise is so quiet how do i know when crit is happening??? bad face looks like bird mask and not in a cool way. dont be fooled by dark japanese theme