Runes:
Personally, I like flat penetration reds, then flat/scaling MR/Armor blues and yellows, based on the opponent laner. Honestly, I find this point a teensy bit subjective.
Items:
Standard rush items. If you are breaking even because you know you can consistently outplay the opponent despite whatever reason, I'd continue building more Damage items like IE or BotRK and then your main defense item. I've been experimenting with forgoing Berserker's Greaves for either Ninja Tabi or Merc Treads and have come to at least some success, so keep that in mind.
Starting Item:
Personally, I only pick Yasuo against heavily skill-shot dependent champions, so I like starting Boots of Speed if I think my reaction time is up for the dodging.
I normally use Doran's Blade though. Smart timing (which I personally believe defines all midlane match ups) favors flat combat stats over utility like movement speed. I emphasize smart timing because of the next point:
How to play:
As a melee midlaner, there is generally no chance to win flat out fights against most ranged champions, at least in early levels. Their being ranged means that they can afford to be way farther back before a fight starts, which is BIG to consider when they can hit you while you are getting in, enemy minions are going to be hitting you while you're fighting because you're standing so close to them AND because Yasuo's main damaging "Ability" is treated as an auto attack, and then they can hit you while you're running away if something goes terribly wrong. Your job as the player is to mitigate at least 2 of these 3 problems, ideally only attacking if you can outright avoid all 3.
Yasuo already has some built in means of avoiding some of these problems. He has his shield to negate initial damage, and his Wall to negate whole projectiles. These are only 2 things, and generally will only be able to counteract 2 of the 3 points I just raised. Yasuo's E however, is key to abusing the hell out of most midlane match ups. Especially at early levels, the enemy midlaner is probably going to use his abilities on the minions. Use this as an opportunity. The moment they use a cool down on a minion means a few seconds of very clear opportunity to fight them as hard as you want while they literally have just used up one of their means of retaliating back. In other words, if you time it with your shield and a good wind wall, you negate all 3 of the problems I listed earlier. You create what I dub "perfect trades" for yourself. I like to emphasize this trick more than ever in patch 4.18 because with less base health, Yasuo really can not afford less than optimal trades anymore, and with less base movement speed, it's really hard to create opportunities for oneself without his E in the first place.
Top or mid?
I'd say definitely mid. The defining point of most Top Laners for me is that they have a means of defending themselves when sh-t hits the fan. Some are super tanks and literally shrug off any damage, others sustain so well that they never are actually in danger, some have powerful CC/disengages, and others may just have dash/blink escapes.
Not Yasuo though. He's not tanky enough and unless you are perfect and rather lucky with your shield timing, his sustain is lackluster without life steal items. His CC is unreliable in early levels during 'panic' situations, and his dash ability is somewhat useless for escaping due to the large amount of distance between the middle of the lane (where enemy minions will usually be) and top tower. While he can work if you play like a balls to the wall all-in top laner and somehow get super fed, he's going to be incredibly unreliable in top lane against enemies (usually gankers) that can capitalize on Yasuo.
No but seriously though, that point about using Yasuo's E to get into the enemy laner's face after they use any ability is super important. If you get REALLY good at doing that, it's the sort of skill that allows you to pull off a lot of stupid shizz that normally will never work without putting yourself in danger
