Abilities

Whisper

• Jhin will reload if you wait for 10s, so you can't sit on your crit shot forever. But, using your abilities (like placing a trap) does reset this timer. So it is an opion if you want to preserve the shot, but you place one of your abilities on cooldown to do so, so it REALLY needs to be worth it.
• While reloading, your attack-move will simply cause Jhin to walk towards the enemy. So, when reloading, you need to walk away with normal right click.

Dancing Grenade

• Its damage increases with every enemy it kills. So try to bounce it off of last hits on minions.
• Another fancy trick is to AA and then cast it right away onto the same minion. Your AA kills the minion, and the grenade thinks that it killed the minion. So it already counts as one stack/kill.

Deadly Flourish

• It has a small hitbox, aim at the feet of enemy champions. NOT at their bodies.

Captive Audience

• Quickly place one on your feet when a melee champion jumps onto you. You can then follow up with Deadly Flourish to stun them.

Curtain Call

• You can actually still use stuff like Heal, Barrier, Farsight Alteration while you are busy ulting. The Farsight Alteration can especially be useful to look where the enemy is or even bait them to AA it.