Dodge his accelerated Q (through the gate): it's his only real poke and it hurts a lot.

Jayce scales poorly compared to most top laners — if you survive his laning phase, you'll be more useful in the late game.

In melee form, he's vulnerable to poke — force him to stay in melee with engages.

His melee E (knockback) can only be used once per switch — once he uses it, he loses his disengage.