If you’re playing as a ranged champion, try to harass and poke Zed down. Avoid over-committing to harassing him though as minion damage does stack heavily.
Invest in early armor when playing as a Mage to protect you from Zed’s damage. This will reduce his chances of killing you.
Try to play to the opposite side of the lane at all times. This will make it hard for Zed to get on to you without using his W. Once he does use his W, move to the opposite side of his Shadow W so he can’t get on top of you.
As Zed is an Assassin, he will look to take down targets that are walking around the map alone. Avoid moving through the river if it’s not warded. Keep a constant eye on the map and do not put yourself in the same area as Zed if you don’t know his exact whereabouts.
Expect Zed to flank and takedown squishy targets with his Ultimate R. Ensure that your flanks are warded when sieging an objective so he cannot get the jump on you.
During the mid-game, Zed will often be in a side lane split pushing. With this in mind, you could use the fact that he cannot impact the fight to start a team fight 4v4 or 5v4 with the numbers advantage.
As soon as Zed hits level 3, his kill pressure increases once he has access to his basic abilities. He can look for an all-in if he’s been able to poke you down beforehand.
Whenever Zed hits level 6 his kill pressure increases once again and he will look to go for kills whenever he has his Ultimate R available to him. Expect him to play aggressive once he gets the level up.
Zed is rather good in the mid-game as he will have 2 items and be able to assassinate any squishy target he comes into contact with. Avoid walking in areas where you know Zed is or has recently been in.