You survive by farming until 6 safely wth Q if need be. Some of the most extreme harass match ups may force you to literally only CS with Q. Don’t let yourself get poked down. The goal of the enemy laner is to put enough harass on zed before he hits 6 so when he hits 6, he can’t just Ult and win. If you hit 6 and you’re sitting at 25% health, then they’ve succeeded. Once zed hits 6, the lane is his. They can no longer afford to just walk up to you to harass because you’ll hit them with a fat combo into ult.
Keep in mind, zed takes a lot of skill. Many will disagree, mainly those that get dumpsters by him because landing the W-E-Q isn’t that hard, but properly setting up an ult and shadow to dodge cc/damage and maximize your own takes a lot of practice. Don’t get discouraged because mastering zed is very rewarding and I honestly find him to be the most fun champion in the game by far. You just need to keep playing him, watch videos by redmercy, LL Stylish, Faker, Azoh and zed montages so you can get a sense of what your kit can really do, and how you can react in certain situations. Sometimes when being ganked it’s more advantageous to throw out the shadow but not take it immediately, and sometimes it’s a double tap. Just watch videos, especially montages. Sure you can’t just recreate those mechanics but it’ll provide a base for a thought process when you encounter similar situations.
As for hitting skill shots, I’ve got only one tip. Q is linear so it’s a hit or miss. There’s no tips for that. Just aim it where you think they’ll be during the travel time. However, your combo can be finessed. When you do your W-E-Q (always in that order) you want to throw your W to one side of them. Never right on them. Once you throw it to one side of them, they will reflexively run the other direction. Well in a diagonal away from the shadow so they’ll run back and the opposite direction. So if you throw it to their right side, they’ll usually run away and to the left. Since you hit your E, they’ll be slowed and you should he able to hit the double Q. That will chunk most squishies all game. You never want to just throw the shadow on them because then they’re liable to run in any direction, increasing the chance you miss your Q. So W right, Q up and left. Vice verse. You also want to use your W as a herding mechanic. Throw it on the side that forces them to run away from their turret, or away from an unwarded area. You’ll win most straight 1v1s so you’re trying to minimize the chance that they get extra resources such as a gank or tower Aggro.
Lastly, sometimes it’s better to hold your Q’s. I make this mistake and so do lots of zeds. When you come out of your ult, don’t just E and Q at them. E, yes, but Q is very easy to miss if you just mash it as soon as you pop out. This is because zed’s ult makes people panic and they’ll start darting random directions to dodge the heavy damage that is your double or triple Q. Come out of your ult, E, then auto them until you get a good sense of where they’re going to be. Sometimes you can Q right out of it, but I’ve missed so many Qs after ulting just because I mashed buttons and that will ruin your ult.