*Skip this part if not interested, it's just some info about me*
Currently sitting at Diamond IV on the NA servers and have been playing for about 3 years. I have been playing Yasuo for a while and instantly fell in love with his kit. Great mobility and very challenging were some of the characteristics I was looking for in champions. Despite what some people think, Yasuo is a highly skill-capped champion that requires you to play to the best of your abilities. One mistake and you're done for. Let's jump to the guide.

Conqueror is currently the strongest option for Yasuo. It is very easy to proc it on the enemy with Yasuo's mobility. However, in a mid-lane match-up, or a difficult match-up like Pantheon or Jayce, you're gonna want Fleet Footwork to have sustain in lane.
Triumph is definitely the strongest of all three options. Bonus Gold and HP, who doesn't love that?
Alacrity is going to be necessary if you wish to have a 1.33 SEC CD on your Q at max level.
Coup de Grace is the best option, as you are going to have LS and will try to be as healthy as possible at all times, and a bit of tankiness which will give you more hp than most enemies.
Taste of Blood, simply because LS keeps you alive.
Zombie Ward because a 6 minutes Ward is crazy op.

As a Top Laner, you are always going to want FLASH and TELEPORT, as FLASH is useful in multiple combos, and for escaping/chasing, and TP is important for Map Pressure.
Unless you are playing Yasuo Mid, TP is the way to go up there!

You're gonna want to start with Q to build up that Tornado fairly early, granting you some CC and ranged damage. However, you're gonna want to Max E, as this is what gives you the chance of outplaying your enemies all day!
There is also possibility you're going to want to max Q, that's in case you decide to play safe and do not want to make any flashy plays.
I pointed out to get two points in your E (Sweeping Blade) for easier outplays at level 3. However, if your enemy is ranged, or if the enemy Jungler has some sort of ranged CC (Like Elise's Cocoon), you're gonna want to have your W (Wind Wall=#ffffff]Parry[/color])to block these kinds of projectiles. This includes Fiora's W (Parry)

Farming is pretty easy. You can farm with AAs, Qs, and E (obviously). Technically, as Yasuo, you should never miss any CS under tower. For Melee Minions,you wait two Turret Shots, 1 AA. For Mage Minions, however, it is one Turret Shot, one AA + Q or E. Very easy. For Siege Minions, you can either wait 7 Turret Shots and AA, or AA at the same time, finish with an AA + Q + E combo. It is fast and easily done, guaranteeing a perfect CSing!

Against Ranged Champs, you're going to want to Q the Melee Minions by last hitting. Your Q stacks stay for 6 seconds, which is usually enough to kill a 2nd creep. Then, either try and poke the Enemy Champion or try to farm the Mage Minions

Your starting items will mostly always be Pot + Droan's Blade/Shield, but it can sometimes be 4x Pots and Cloth Armor if you really think you are going to get stomped in lane against an AD opponent such as Pantheon.
For the First Buy, you should wait to have around 1400 Gold to buy a Zeal AND a refillable potion, this thing is very cost-efficient.
However, if you are getting stomped in laneby either an AD or AP Champ, rush Ninja Tabis or Mercury Treads accordingly, as living is the number one priority. If you don't die, the enemy doesn't get fed off of you, even if you are behind in creeps. For AP burst Champs, Hexdrinker is also an option, which I like less because it slows down your build quite a bit.
Your first completed item should always be Phantom Dancer (PD). This item gives you sustain, attack speed and the Crit. Chances you need to beat your opponents.
Next, you are gonna want IE to get that juicy 100% Crit. Chance.
Third is going to LifeSteal (LS). You want this so you can stay on the map longer without having to back too much, allowing you to pressure for a longer amount of time and enabling your team to play around the map.
GA is a viable option, as it allows you to dash in, kill the enemy, die and revive after 4 seconds. Being focused is not really a problem, and sometimes it even dissuades enemies of attacking you because they think it's useless because of this item.
QSS -> Mercurial Scimitar is good for Cleansing point and click CC. Other CC can easily be prevented with Wind Wall, but it is very useful late game. This item can replace the GA if you do not get bursted too easily and they are AP heavy with CC.
Maw of Malmortius is only to get if you bought Hexdrinker, can still be convenient with the LS it provides, as well as the Shield. This item can replace the GA if you do not get bursted too easily and they are AP heavy with burst.
Randuin's and ThornMail are situational. If the enemy relies on Crit. Strikes, buy Randuin's. If the enemy has a lot of LS, buy ThornMail.
Spirit Visage is good if the enemy team has 2 or more AP champions (excluding support, who usually go utility rather than full damage, except Lux, Zyra etc.), these usually being AP Solo Laners.

The reason you do not need two Atk. Speed Items is because you're gonna get . Those allow you to attain a 1.33 SEC CD on your Q when it is level 5.

Here are my Tips and Tricks for Yasuo!
The most basic and easiest trick which a lot of Champions have: AA cancelling. AA + Q, or AA + E, dealing damage faster.
Tornado + AA/E + R: This combo should only be used if you are close enough to your target. You knockup the enemy, either AA/E for more damage, and then press R. This will let you deal more damage and assure a kill.
W + Q: Wind Wall + Q let's you surprise your opponent. It almost completely nullifies the Q animation, letting you surprise your enemies.
W + E: just like the combo right before, this one let's you dash trhough your Wind Wall, making you look amazing!
Q + E: very easy, it helps you farm under Tower, or deal damage faster.
E + Q + FLASH: also known as the KEYBLADE, this requires you to have your Tornado ready. Instantly surprise your enemies with this!
Unknown fact: Yasuo can block Fiora's Parry (W)
Charge up your E (Sweeping Blade): before dashing onto an enemy champion, charge up your E by using it on minions, this will deal more damage.
You can also use this to closegap on minions for chasing an enemy.
Your Wind Wall grants vision! Use it to your advantage!

Keep in mind that the AIRBLADE does NOT work anymore! When ULTING, Yasuo RESETS Steel Tempest's (Q) cooldown!
Yasuo's Wall dashes as well as these tricks in one video. Play Video

Thank you, you who has read this whole Guide! I hope it was useful to you and that it will help you improve as a Yasuo player! Tell me what I can improve on! Comments and Critiques about this guide would be appreciated, as this is my first one ever!
Thanks again, and have a great day/evening!