I play riven because its a playstyle i like.
Its a melee champion so you can't just play her glassy with 1900 health in end game.
Check out this guide and don't downvote until you tried it.
This is my first guide, and i didn't figure out how all links and pictures worked, but it should work anyway right?
And yes this build works for ranked i used it alot of times.

My english aint the best but i think most of you will understand what im saying.

For runes i pick my standard that i use on most AD champions.
[Greater mark of desolation 9x
Greater Glyph of shielding
[Greater mark of resilience 9x
Greater quintessence of desolation 3x

I go 21/9/0 on riven.
I don't think that points in utility works better than points in defence

Exhaust & Ignite:
you can chose between exhaust and ignite its all about your playstyle

Ghost & flash:
I prefer ghost before flash i got my dashes with Broken wings and valor, And ghost will give you kills, Help you to get to a chased teammate or make you escape and keep you from feeding :P
Flash will just give you a good escape and maybe a kill, But its all about playstyle

I max Broken wings first, i maxed ki burst first when i started to play riven but noticed broken wings give me more damage and makes it sooo easy to farm, in level 9 you can clear a whole minion wave with 3 wings and one ki burst.
Harrass, You just jump hit then do it over 3 times then you use valor to back before you lost to much health.
Riven is a very aggresive champion, if not played aggresive you will fail the lane thats why i start out with a regrowth pendant that i later build into a philo stone because its just 300 gold more and if you farm like you should it will be no problem to get boots of speed, philo stone and a brutalizer on first way back

I tried alot of different starting items like dorans blade, dorans shield, lifesteal(build into wriggles) and regrowth pendant(philo stone).
And i still feel like health regenation is the one that works best.
Brutalizer - Cdr, armor penetration and damage, you need it all.
ionian boots of lucidity - Cdr what more can i say
Infinity edge - i found out without building really tanky you need those big crits to deal enough damage.
Warmogs - as i said in the intro you can't play this champion glassy.
Atmas impalor - Why not? you got alot of health and the armor works just fine against auto attackers.
Ghostblade - Build from the brutalizer, a nice activation and you need all stats that you get from ghostblade.

Now to last item.
Guardians angel - Both magic resist and armor, Got a nice passive thats awesome if you use it right.
Bloodthirster - You feel that you are unstoppable and nothing can stop you then you get this item, Never get it when you are dying alot.
Banshee's veil - against heavy ap casters like veigar, leblanc. I get this item most of the times

Black cleaver: Since you wont auto attack to much before you use your combo i wouldn't pick this item, its more for ashe, cait and other auto attackers

Last whisper: Get this one when facing a tanky team, works really great :)

Thornmail: you got no use of this in my opinion its better to get banshee's veil or Guardians angel since those 2 got awesome passives

Force of nature: I will only say the same as i said on thornmail

Randuin's Omen: Works really great if you got problems with those damn auto attackers

Madredz bloodrazor: You don't got that attack speed and you don't auto attack that much to use all of the Bloodrazors damage, fits better on kog maw and tristana

Now to the most important!

Rivens playstyle is alot different from any other champions.
Without the knowledge of rivens playstyle riven will be useless and they will call you noob tell you that you got no damage riven sux uninstall game and such stupid stuffs.
Thats why im here to tell you ;)

How to play riven like a god
First of all you need to play aggressive or you will be pushed out of your lane, just harrass like i told you in the harrass part.
And when you got the lane make sure you don't lose it. you will need to go solo on top lane when you play riven, she doesn't fit anywhere else except maybe in the jungle, but if you ask me riven don't got a good enough gank to fit in the jungle either so solo top it is.

Teamfights - You should never engage with riven, its waste of power since you can easily kill their ap carry or ad carry in a couple of seconds if you get the chance to.
After your tank/off tank went in to their team use valor and Ki burst then you go straight for the ad or ap carry with your broken wings, Remember to auto attack once before you use broken wings again with this build ulti and your passive you will have like 500 damage every hit after you cast one spell, Don't waste that damage.

If you really wanna jungle with riven skip the health reg and start out with a armor and 5 health potions build that armor into a wriggles lantern when you can afford.

Jungle path:

Wolfs
Wraiths
Double golems
since you don't need the blue buff tell mid to come help you with it and then give it to him, you wont be able to solo the blue buff with riven without going base once.
Lizard
Wolfs
then just continue like that.

Ganking:
with riven you can gank after double golems if you got enough health,
Just run into them and use ki burst and as i said riven got no good gank so i don't usually jungle riven if its not really needed.