Don't let Brand harass you for free. Try and stand back and out of range of him so he's unable to attack and harass you with his W. Ensure that you remain healthy otherwise you'll never be able to fight him. A good time to fight Brand is when he's out of mana or has an ability on cooldown. This will make trading much better for you as he will not be able to dish out a lot of damage (or possibly stun you if his Q is on cooldown) as he'll have 1 less ability to use.