Thresh

You don't have to reactivate your Q (Death Sentence): sometimes keeping the enemy at a distance without dashing to them is safer.

Throw your Lantern (W) ahead of time toward a struggling ally — the pickup range is generous and can save a jungler who's diving.

The combo of E (Flay) push then Q is more reliable than raw Q: the knockback/slow from E makes the hook easier to land.

E's passive (Flay) charges bonus damage on your next auto — in lane, a charged auto hits very hard at levels 1-2.

Your R (The Box) slows massively on the first wall hit — use it after hooking to prevent the enemy from Flashing to safety.

Stay behind your minions: Thresh's hook is blocked by units, unlike some other hooks.

Don't forget you can click on his Lantern to block it — you can stand on it to prevent Thresh's allies from taking it.

Punish him when he steps forward for a Flay auto-attack: Thresh is melee and vulnerable when he tries to proc his E passive.

His hook has a visible windup (he pulls his arm back) — use that moment to side-step.