Build and Runes
Avoid staying in lane with low health, as Garen’s ultimate will deal massive damage to a lower health target.
Try your best to keep your distance against him, because his spin deals a ton of damage if he catches you with it.
Poke down his passive so he has no regeneration.
Garen suffers greatly from hard CC and high-mobility ranged champions. Use this to your advantage when picking your champion.