Teemo vs Yasuo

Save Blinding Dart (Q) for the champion who relies on autos, right as they start a trade: blinded, they miss their autos.

Stand still for a moment to turn invisible with Guerrilla Warfare (passive), then strike first: when you leave invisibility, you gain attack speed.

Save the Move Quick (W) sprint to escape a gank: you have no dash, and its bonus isn't lost when you get hit.

Place Noxious Trap (R) on busy paths: jungle entrances, around dragon and Baron, river brushes. Stealthed, it slows and reveals the enemy who steps on it.

Hit him with a cheap attack to trigger the Way of the Wanderer (passive) shield, then start the real trade: otherwise, it absorbs your best damage.

If you have projectiles, save them for after Wind Wall (W): it blocks them all for 4 seconds, on a 25 to 17 second cooldown. Other spells go through it.

Don't stand right behind your minions: each one gives him a target for Sweeping Blade (E), and he gets closer to you with every dash.

Get out of the line of his whirlwind, the third Steel Tempest (Q): without a knock-up, he can't cast Last Breath (R).

Judge his threat by his crit items more than his level: Way of the Wanderer (passive) raises his critical strike chance, so each crit item does more for him.