Autoattacking in between each Broken Wings will allow the most amount of sustained damage as you consume Runic Blade stacks to deal extra damage.
Since the skill produces three charges, which is exactly her maximum, you may wish to complete it to initiate a fight with her knockup, following up with auto-attacks and her other skills.
It is a good idea to learn how to auto-attack cancel with Riven. This can be done by using any of her abilities immediately as the damage is applied during an auto-attack. Because Riven's auto-attack animation is longer than the time it takes for the damage to actually register, doing this can cut off more than a second from a Q>AA>Q>AA>Q>AA combo. You must apply a new attack command in between each "Q" to obtain the maximum possible speed.
The best way to go about this is by auto attacking, immediately pressing Q when the damage of the AA is dealt, while hovering over the target. As the animation of the Q is playing, order riven to move anywhere beside the target and immediately right click the target again. Both of these clicks should happen before the animation of the Q is finished. This will allow both the animation of the Q and of the auto attack to be cancelled and will significantly increase your burst sped once mastered.
Some combinations of abilities allow for better speed. For example, any cast of Broken Wings can be used while the animation of Wind Slash is still running. The fastest way to burst down a squishy target if you can do it without additional auto attacks is E > R > hydra > W > Q > R > Q > Q. Every ability in this combo will cancel the animation of the ability before it, except for the second R and the third Q.
Blade of the Exile lasts for 15 seconds so use it at the start of the fight instead of the end of the fight.
Using Broken Wings in conjunction with Valor will give you small boosts of mobility as they move you forwards a bit. This is a very efficient way to move around the map, as your moves cost nothing. Broken Wings, however, allows you to click on the mini-map and use it to continue moving, while Valor will cancel your move actions.
Beware using skills right before a skirmish, as your abilities will be on cooldown and thus be unavailable for the fight.
Broken Wings can also allow you to chase an enemy so that you can knock them up.
Make sure you test what map terrain is jumpable over. An example being: The walls separating the river and the jungle in Summoner's Rift.
Be aware that Wind Slash has a cast time and a travel time as well, so you shouldn't waste it on enemies who are just about to leave its range. Try using smart cast to save precious seconds in aiming the ability.
Wind Slash deals maximum damage to multiple opponents at or below 25% maximum health, therefore use Wind Slash to finish off enemies who are fleeing or deciding to stay despite low health.
Riven is an all-around strong champion in top solo lane due to her ability to avoid ganks with her mobility, her no-mana costs, and her instant cast shield. Play aggressively and use Valor to shield your way through harass.
Broken Wings resets her auto-attacks on each cast and it is useful to cut off the animation. (Tested under attack speed Slows)
Broken Wings' dash speed is roughly equivalent to 475 movement speed. At 550 movement speed, however, simply moving is faster than using Broken Wings as a method of faster travel.
Ki Burst can be used to cancel the animation of her auto-attacks and the crescent activation of Ravenous Hydra. However, its own animation cannot be cancelled.
Don't use Wind Slash right away if the target is no longer stunned or knocked up, because you risk missing them if they flash away or simply dodge it. As the range is quite long and shaped like a cone, it's easiest to hit when the enemy is not right next to you, so it may be wise to hold on to it until they try to escape.
Riven's entire kit benefits from bonus attack damage. Building heavy attack damage items will not only help maximize her damage, but also increase her survivability through Valor.
Riven benefits heavily from cooldown reduction which will allow her to use all her moves more frequently. However, at later levels, Riven is likely to have at least one of her abilities available for use even without cooldown reduction due to preferring to take her time to autoattack between casts and the cooldown of Broken Wings starting even if you delay the latter two casts of it, which make the stat less needed then.
Having a way to slow the enemy or speed yourself up is mandatory on Riven.
However, Riven is very good at dealing damage while chasing as Broken Wings moves Riven forward both doing damage and giving her an opportunity to get in basic attacks without losing too much distance. The dash distance is unaffected by Riven's movement speed, so building movement speed items are not as important on Riven as on most other melee champions.
A Frozen Mallet is good for this, since you will be using auto attacks in between abilities to maximize your passive (none of your abilities will otherwise proc the slow). It also gives you health which is a must since Riven is squishy when stunned, sealed, blinded, or otherwise prevented from auto attacking or using her Valor or Broken Wings to escape and/or shield.
Randuin's Omen works very well on Riven as while she may have four ways to dash, they are all short-ranged and Broken Wings loses damage if used fairly far-away from the enemy, and she is still a melee champion that can be damaged by ranged champions without reprisal until she gets close enough. Valor can move Riven close enough to a target to slow them with Randuin's Omen and then walk close enough to have casting Broken Wings move her into melee-range while damaging the target.
Guardian Angel is an excellent one-stop defensive item, and its passive as well both armor and magic resistance can tide Riven for a good while before she may require other defensive items.
Maw of Malmortius is sensible for Riven if she is fearing magic damage - the attack damage is obviously useful on her while the shield and passive works well with Valor and the life steal from The Bloodthirster in helping you survive a bit longer in a close-fight.
Riven does only physical damage, so a Last Whisper is a good item to counter the armor that should be built against you.
The Black Cleaver is also a great item on Riven, as Riven can easily stack its passive with her combos, not to mention the extra 200 health and the 10% CDR the item gives are very useful.
Youmuu's Ghostblade should be used after the 2nd hit of Broken Wings or during the last frame of animation of the 3rd strike to avoid losing precious seconds.
Stacking Doran's Blade early game helps due to its sustainability and AD.
Riven is great for Twisted Treeline. Her strong early game, and mobility with her abilities help her to dominate top lane, as well as give her great ganking ability. She also performs very well in the jungle. After netting a couple of kills early, you should be able to snowball pretty hard.
Do not underestimate Riven's defensive stats, even if she is building straight damage. Valor scales off her bonus attack damage and has a considerably low cooldown late game.
Don't forget about her mobility and overextend when chasing Riven. Her Broken Wings allows her to dash up to 3 times, and her Valor allows her to dash and grants her a shield. This can create a very long gap between you and Riven.
When you are low on health, do not face Riven as her Wind Slash deals more damage the lower your health is. If you're still squishy and you know she has acquired her ultimate, do not linger around with below 25% health even to turret hug, as she can, and will, flank around to kill you with Wind Slash.