Don't always start with your e or q. Each one is better in different situations. In a lane where you don't want to play aggressively start with your q, but if your opponent is someone you thing you can easily out trade at level 1 I recommend starting e. When using e leave yourself an out. You don't need to e to every minion on your way to the enemy champion. Leave some minions un-e'd so you can go in and out quickly. Don't take windwall (w) if you don't need it (the earliest you should take it is level 3). If you're in lane against someone who doesn't have any ranged abilities (or if you can easily dodge their abilities) you shouldn't take your w until level 4 or 5 (depending on the jungler's kit). When you go for a trade make sure your shield is charged (why would you take extra damage when it can easily be prevented).
If you are going to be in a lane where you can't easily engage the enemy I recommend starting doran's blade because in a lane where you really won't be doing anything but farming it provides more sustain than extra potions will. However, if you are in a lane where you want to and can play aggressively I recommend starting longsword and 3 potions because you will do more damage. 3 potions tends to be more than most of your opponents (especially in mid lane) will start with. So while you will not have as much sustain as doran's blade would give you you should be able to out sustain your lane opponent.
Finally practice makes perfect. I haven't played yasuo in quite a while so I'm really just working off of memory. Try different starts and see what fits you best.