Riven is a champion that relies on her cool-downs. So be wise on how you use your abilities. If you spam all your abilites in a fight all of a sudden, you can lose that fight.

First start out with your q. Then when you hit level 2 and 3 get your w and e. I would recommend to max out your q first then your w and lastly your e. Max out your ultimate whenever you have the chance too.

When using Rivens "Q" she gets a damage bonus each time you use it. So when your attacking a champion hit "q" then hit with a basic attack because it will deal more damage. Everytime you hit Riven's "q" do a basic attack in between.

When using Riven's "w" and "e" they're helpful when an enemy is running away because the "w" stuns them and "e" charges at them.

Tip- What I usually do when im aout to charge at an enemy is first use valor (that will give you a shield for a couple of seconds. Then i use "w" to stun the enemy so they i can attack first. Then i just use "q" and do basic attacks in between.

-Be smart when using the abilities like i said
-Dont rush in to fights because Riven doesn't have very good health so chances are you'll probably lose
-Your "w" is very helpful in team fights so always use it
-When you have to run away use valor and then use q twice that will help create some distance (always click in the direction you're going when you click your "Q' so you go the way you want to go)

Pros:
-powerful with the right
items
-easy to play
-OP when you get the right items and if fed
-somewhat balanced

Cons:
-melee champion so you have to place yourself correctly or else you can die
-not strong by herself
-relies on cool downs
-long cool downs
-weak against ranged champions