Your main combos will revolve around your passive 4th shot or W by either maximising your 4th shot damage or hitting your W as fast as possible.

for your highest damage combo you need 2 shots left
AA + Q + Trap behind them + W as they walk into the trap then 4th
This combo gets as much damage off before your 4th shot as possible while leaving little room to avoid it without mobility. Its important to note you only really get this whole combo off in ideal situations where the target has no mobility and you hit your W but in doing so will delete any squishies and shred tanks. Also the trap will only detonate after the root ends which puts you at risk of not getting the 4th shot if you try to wait for the trap.

A good thing to note is where possible its good to Q before 4th shotting in quick trades, this plays around the missing health damage on the 4th shot like the maximum damage combo, however if the target has the mobility to get out of range between your Q and 4th shot its better to take the 4th shot instead of risking losing potential damage.

Another combo is to setup a Q bounce on low health minions then after it bounces of the last minion to the target champion start your W on the champ so the Q hits them just before the W giving a near instant root, this is a great combo although difficult to execute due to the timing. However if they dodge the W or your miss it its fine cuz the Q bounce will usually win the trade since they put more focus into dodging the W instead of evening the trade.

Another combo for half health targets is to AA+Q then move back a bit and W, if you hit the W INSTANTLY ult giving you at least 2 free hits, then if you hit the 3rd you usually kill the target and hitting the 4th after the first 2 is a guaranteed kill on any adc, if the supp tanks your ult shots your supp can step in to either punish that by killing the supp/getting them so low they can't tank, or holding them in place/pulling them away for you to hit your shots.

Placing a trap on a control ward is always great as most melee champs will back up from the ward once the trap detonates buying more time for you to either turn on the adc or fight the champ off the ward, it also is usually a good spot for a trap in a bush to slow down ganks/roams.

For the tri-bushes its best to put the trap just slightly off-centre in the direction of you, meaning if they pass by tribush staying on their side of the map it wont detonate, giving you a bit of vision, but if they try to go towards you the trap detonates allowing you to root the target or buying you time from a gank.

Teamfighting as jhin for the most part is the same as other adcs, sit behind the frontline hitting the closest enemy while paying attention to incoming skillshots and assassins, but with jhin you can prepare for a fight in a number of ways. You can setup traps in the correct spots, usually choke points or areas u think an assassin might try and flank, but also setting up the minion wave for a Q bounce, or positioning yourself only within W range so the enemy team has no idea where you are or where you will enter the fight from, if you are fed enough u can go to 2 shots and AA+Q+4Th the enemy adc to death.

Also don't forget if you are coming to lane after a recall u can W the wave to catch cs under tower, this is pretty simple but I don't see many jhins doing this, and it has saved me quite a few cannons. On that note u should get into practice of moving you camera to fights you are moving to, as you can help get picks with your W or even save a teammate.

If you are roaming around the map between lanes it is always a good idea to just leave a few traps for info, placing them between camps or infront of them to tell where the enemy jgl is or if anyone is also roaming, although be careful not to facecheck bushes especially if you know the jgler is nearby, or if people are missing from lanes.

Also if you win lane, push out and get the first tower, its always a good idea to swap with your mid so you can start pushing out mid while your mid gets some free farm, as the enemy bot will almost always push out the wave you just used to take tower so the bot wave will be moving in your direction. This helps put pressure off your mid if they are losing lane and add pressure on the enemy lane, keeping them from roaming without you taking their tower. It also allows your support to begin roaming top or even back bot if your mid gets the enemy bot low. Being able to swap lanes before the enemy team puts a tempo lead on your team as you and your support are able to shove mid wave and start getting vision on objectives before the enemy.

Last tip, at EVERY stage of the game your 4th shot does more damage to drake than smite as long as its below 1k HP, mid-late game u can do up to roughly 1.2k dmg, also if you can communicate with your jgler u can combine your 4th shot and smite to deny any attempts to steal drake even vs chogath or nunu (but not both nunu q cho ult and smite) or steal a drake, the same applies to your ult 4th shot.

I may have missed a few things, or gotten a few things wrong, I am only speaking from my experience with jhin so take this with a grain of salt. If you have made it this far thanks for reading my guide. Oh and if it wasn't obvious, I don't like running 80% crit if I'm not building lethality, just personal preference.