so this is my first build but it works well for riven. if you play Riven then you know you need cool down reduction and some life steal. The cool down reduction lets you to use you abilities non stop. You are also going to need life steal since Riven has no healing abilities.

So the Runes are simple. attack Runes since all of her damage of her abilities is based of AD. the Armour runes to help you last longer in a lane. attack speed runes so you can deal damage faster.

so the the way i have these allows you to have a good health regeneration this helps you get over how squishy you are early game. it comes down to having AD, attack speed and and health regeneration. the other ones are up to you.

cool down reduction helps Riven out so much allowing you to pull of one ability after another and do large amounts of damage. the Brutalizer helps you out a lot with this then it builds in to the Ghost blade which is even better. if you alone with a Champion and you want to kill him make sure you active the Ghost blade's ability allowing you to chase down the champion and kill him.

so to play Riven do not spam an ability that will not do the most damage. use broken wing the auto attack then broken wing then auto attack the broken wing then auto attack then Ki burst auto attack then dash auto attack. bu this time if you have all the cool down reductions your broken wings should be ready to go again and you just repeat. your ultimate should be used if the Champion you are attacking. its works well on a Champion that is just out of range or about to be near a turret you hit him with this if he has low health and he is not getting back up. the order you get your skills. i suggest you get broken wings first because it does the most damage overall.

so i use heal and exhaust. it doesn't really matter its up to you

so overall the best way to build Riven is to build cool downs AD and life steal. you won't need much other then that.