Hi, I'm (currently) just an average gamer like you, not yet lvl 30, so obviously not ranked, but I'd like to share my build for this new character all the same. This point of my build is to maximize attack damage, attack speed, and life steal with 100% crit chance. I know this guide won't be as fancy or big as other guides but hopefully helpful all the same. Anyway here is my first guide, enjoy :)

So for Yasuo I think the typical flash/ignite combo works great. By now everyone knows the basic utilities of these spells so I don't need to go too much into detail here.

Other viable options are Ghost, Barrier, or Exhaust.

Ghost is a decent backup option for the increased movement speed both to catch or outrun your enemies. Barrier gives a little more survivability in a fight, and Exhaust helps to beat down other AD characters.

Again, some defensive runes to keep him alive early game. I split the marks between Attack speed and damage because his cool down for Q is based off attack speed.

Steel tempest is your "Bread and Butter" as the Dev's put it. It helps with your pokes and counts as a basic attack. This allows it to crit, apply on hit affects, and so on. *Note: I believe this is only for the first two strikes and that the third strike is counted differently.*

Wind wall only requires one early point for its usefulness and the other abilities are valued above this one.

Sweeping blade is both a good closer and escape strategy. It dashes a fixed 475 units, with can get you into trouble around turrets. While the cooldown time for this ability is quick remember that it takes 10 seconds before an enemy can be targeted with it again.

Last breath is your most important ability, put a point into it every time it becomes available. It give good (albeit quick) single or multi target CC and bonus armor penetration afterwards.

I'm never sure how to start a build but I tend to like boots and 4x HP potions as this usually lets me stay in lane until I'm between level 5-7.

Phantom Dancer - This is one of the best items for an AD melee. Attack speed, Crit chance, and movement speed; Plus no hangup on minions.

Ravenous Hydra - I put this in to help farm faster for gold. Life steal, Hp regen and AoE attack are useful for this character.

Infinity Edge - Is a must for this character. He essentially lives for crits given his passive. This will raise his critical damage from 190% to 240% (he loses 10% due to passive). +70 attack damage is a big help too.

Zephyr - All around great item combo with Phantom Dancer. This gives the rest of your movement speed bonus so that you can replace the boots at the end as well as another 50% attack speed. Tenacity is a useful passive to help cut down the CC length.

Maw of Malmortius - This is your defensive item in the build. I choose this due to the damage and MR your get from it, as well as the useful passives. The shield with help with perseverance at the end of a fight, while the extra damage due to missing life with help you win those close 1v1 duals.

Blade of the Ruined King - This is your final item for this build, you will swap out your boots for this item. I like it due to the extra 20% attack speed you get over the berserker greaves, the extra life steal, and the bonus effect damage its unique does. This is that icing on the cake item to just make sure you keep going strong late game.

There are several items I have seen in other guides and suggested by the Dev's that could be useful for Yasuo, I won't go into discussion about the pro's and con's for these as I don't have much experience with them on this character to tell you.

The List:

Last Whisper
Youmuu's Ghostblade
Bloodthirster
Statikk Shiv
Trinity Force
Frozen Mallet