This build for riven grants her good mix of damage and durability at the begining of the game and making her a very powerful off-tank eventaully.

The must items are Tiamat, Wriggle's Lantern and Frozen Malet.
The shoes is by need, if the team has more AP champions so take Mercury Treads but if there is more AD Champions, take Ninja Tabi.
about the late game items, it's also by need, Randuin's Omen and Force of Nature are good but must items, you can also purchase Thornail, Hexdrinker, Spirit Visage, Warmog's Armor.

You can learn your skills by need also, but u must first max Ki Burst for the stun and damage, also it's cooldown is reduced, then if you need more defence max Valor otherwise max Broken Wings.
And most of players are not aware of...is that the ultimates damage(second part "Wind Slash") is increased based on the % of the missing health of the enemy, so use the second part of the ultimate (Wind Slash) as the killing blow, but activate it early in battle for the extra damage.

I recommended this spells because riven does'nt need falsh...because she can use the dashes of Valer and Broken Wings to chase or escape.