my Name is Kuro XI and i play on Eu West im currently Platin 2 climbing the ladder rapidly, im here to show you how to style on your enemies and gain LP with Riven at the same time.

Pros

+Fun to play
+High Damage
+High Mobility
+Strong Mid and Late Game if played right
+Survivability
+Good AoE
+Good CC
+Strong Snowballing potential

Cons

-Weak Early
-Realy weak to CC
-Hard to play in current Meta

Masteries are realy important on Riven, you will notice this when you once forgot to change your Masteries or Riot servers are lagging and then you play with AP Masteries which realy sucks.

Let's talk Runes baby, nothing out of the ordinary here, get your CDR Runes in Sync with your Build and it's all good your Gylphs are normaly fully CDR but u decide this.

All these Items are viable on Riven but it depends always on the Situation i already wrote some notes, standing by the side of the Recommended Items

This is the reason why Autoattacking after you're abilitys is so important, it adds alot of damage to your basic attacks especialy for early to mid game trades.
This is your main damage source, it can be activated 3 times the first 2 are for damage and mobility and the third one also knocks back, so it can interrupt spells for example Shens ulti. Also you can jump over walls easily with your third jump.
This is your main CC ability i often see myself flashing into a group of 3 to 4 Champions to get this nice AoE stun of it surely got a short range but you get used to it. Also it's one of the reasons why Riven Counters Yasuo so well, right before you ulti you stun him so he can't Wind Wall it, also using this so my target doesn't flash my Wind Slash.
Valor got hit hard by the Nerf but it still is usefull for example alot of Champions got Problems against Pantheons early game harras from his Q but if u take the CDR runes everytime he throws his Q on you you can just Valor and absorb the damage till he runs out of Mana and you can easily then force him out of lane.
For me it's one of the best ulti's in the game and probably the best ulti for 1vs1, but never waste this spell the CD sure isn't that high but if you activate this spell and the enemy for example Renekton just doubble E's away. Use this ability if the enemy just used his escape ability or is engaging on you, if you farmed well you should be able to 1v2 alot of Champs, if they dont bring alot of CC.

Early Game

It's always depends on the Champion but it can't Hurt to play passiv and farm as good as possible, atleast until level 3-5 but even then there are some Champions you shouldn't duel, Renekton, Volibear Cho'Gath and if you arent ahead after level 6 even Nasus can easily duel you (this is if both Champions are played equaly good). At level 6 you should be able to kill most other Champions the combo's to use are listed farther below.

Mid Game

You should probably still be farming and often push the lane and roam, it can be hard to gang mid because of the short lane but before this i often deep ward into the jungle and often i even find myself a Jungler to kill, still you gotta know yourself if you should go into enemy jungle if you are confident you are strong enough then go for it this is part of snowballing the game.

Late Game

If you are ahead you can probably faceroll but try not to tank the towers since you are a Riven player so you are the most important person in the team, nah seriously if you get focused by the tower good chances are the enemys are also gonna focus you, because everyone hates Riven almost as much as Teemo. But well it's not like Riven can't tank a tower but most of the time it isnt worth the Risk only if you are completly Stomping and don't even care anymore.

If you and your team is even or behind often peeling for your ADC may be a winning factor or flashing onto a enemy carry and totaly destroying him which is pretty risky. But if you are behind i wouldn't go full glasscanon maybe a Randuins could help.

Here is the part i tell you about the combos and when i use them.

Engaging: This combo is the fastest and often suprises the enemys abit because of it's speed
E-R-Q-AutoAttack-W-AA-Hydra-Q-AA-E-R-Q well this is a full combo most player's wouldn't even survive until the secound Q so you also ulti way earlier. You can also use a flash at the start to cath up which adds to the suprise level (most player's can't handle this).

Normal Lane Trade: E-AA-Q-AA-Q-AA-W-Hydra-AA-Q-AA-E well this is just basic stuff mostly used against tanky people like Nasus Malphite you can also use you W and Hydra part earlier and retread after, depends if you are winning or losing the trade.

Bush Camping: For newer Riven player's i suggest warding the bush you are staying in because you are probably going to Q out of it without wanting to you Start with a R-AA-Q-W-Hydra-AA-Q-AA-R using your Execute can be used earlier or later you gotta practice Riven alot so you know yourself when to use it. If they are still alive after this combo you can still chase them down with you'r e and last Q but chances are if you are Camping for someone you are probably decently strong and they should Die right away.

Well these are just 3 of the many Combos of Riven, the basics are Autoattackreset's and animation Canceling after the damage has already hit, Your E is essentialy especialy when chasing someone down before using ulti i 90% of the time use E right before it so you dont have cast time.