I'll try to detail the best gameplay of Riven.
First of all, if someone can help me to translate it to english french build. Thank you contact me.
Enjoy yourself by reading this guide. All tips are welcome

- 9/20/2011 :
Birth of the build

- 9/21/2011 :
I added the class "Pros and Cons"
Upgrade "Runes" and "Summoner spell"

- 9/24/2011 :
Update mastery trees
Update skill sequence
Update runes build
Update items purchases
Update runes, skill sequence and summoner spell

- 9/25/2011 :
I tried some new mastery trees and new runes page. I change a bit Items purchases and adds Atma's Impaler

- 10/27/2001 : Updated invoc's spells, items and skill sequency and runes.

League of Legends Back Story:

In Noxus, any citizen may rise to power regardless of race, gender, or social standing - strength is all that matters. It was with committed faith in this ideal that Riven strove to greatness. She showed early potential as a soldier, forcing herself to master the weight of a long sword when she was barely its height. She was ruthless and efficient as a warrior, but her true strength lay in her conviction. She entered battles without any trace of doubt in her mind: no ethical pause, no fear of death. Riven became a leader amongst her peers, poster child of the Noxian spirit. So exceptional was her passion that the High Command recognized her with a black stone rune sword forged and enchanted with Noxian sorcery. The weapon was heavier than a kite shield and nearly as broad - perfectly suited to her tastes. Soon after, she was deployed to Ionia as part of the Noxian invasion.

What began as war quickly became extermination. Noxian soldiers followed the terrifying Zaunite war machines across fields of death. It wasn't the glorious combat for which Riven trained. She carried out the orders of her superiors, terminating the remnants of a beaten and fractured enemy with extreme prejudice. As the invasion continued, it became clear that the Ionian society would not be reformed, merely eliminated. During one bitter engagement, Riven's unit became surrounded by Ionian forces. They called for support as the enemy closed in around them. What they received instead was a barrage of biochemical terror launched by Singed. Riven watched as around her Ionian and Noxian alike fell victim to an unspeakably gruesome fate. She managed to escape the bombardment, though she could not erase the memory. Counted dead by Noxus, she saw an opportunity to start anew. She shattered her sword, severing ties with the past, and wandered in self-imposed exile - on a quest to seek atonement and a way to save the pure Noxian vision in which she believed.

''There is a place between war and murder / in which our demons lurk.''

Pros

- Great dps early game
- Great mobility
- Nice aoe stun with "KI BURST"
- Strong damage
- can escape easyly

Cons

- Cannot engage teamfight
- You have to skill chain correctly to do some damage


Broken Wings :
- Give to Riven a great mobility
- Fast damage
- Don't forget to give an auto attack between each level of this skill

Ki Burst :
- Strong aoe damage
- Strong aoe stun
- Great cooldown at level 18
- good farming

Valor :
- Great skill to engage fight
- Give a bit defense with one shield
- Allows you to avoid various attacks

Blade of the Exile :
- Increase Riven's damage
- Great aoe damage to finish low level ennemies

coming soon...

- I use ghost to upgrade chasing or to escape a lost teamfight.

- it's really usefull to increase ur damage done early game.

You are early game on lane ... :
- you can harass ennemies with Valor + Ki Burst and go away with Broken Wings and continue like this until you have an opening to finish the ennemy.
- if you are in duplicate with a carry, he can enjoy your combo Valor + Ki Burst (=stun) to inflict damage on the ennemy.

If you are good early and did some kills ... :
- I always engage fight with Valor to increase the survivability of riven + Blade of the Exile + Broken Wings (x1) + Ki Burst + Broken Wings (x2).

If your are in difficult during a fight ... :
- Wait for the ennemy be near your, give a Ki Burst to stun him and you fast Valor + Broken Wings (x3) to escape. If you need, you can use Flash more.

We should not underestimate Riven's passiv and his ultimate. They 2 skills combined make really great damage.
As far as a fight, Riven is more and more damage, finishing with his ulti when all the enemies targeted are lowlife.

With the Q, do not forget to give a self attack between each stage of skill.

For ulti, it is essential to trigger the second ability when opponents are low life.

Pros :
- You can give the first blue for your midder lane. It given a good advantage on mid.
- You are not dependent about blue buff
- you can gank fast with a great stun


Jungle route :
1 - You help mid to get blue with the soloer.
2- You go at wolfs
3- You go at wraiths
4- You go kill the two little minion aroud the red golem.
5- You go kill both golem.
6- You back and buy Long Sword and Boots and some health potions.
7- You can go red buff and gank if someone need it.

I will continue to work on the translation of my build. I would bring you more information about this amazing character that I found: Riven.

NB : if someone can help me to translate it to english from french build. Thank you contact me.