When laning as Riven try to pick up the early advantage if you can. If the lane is going to be hard go cloth 5pot or something to stay in lane till 6. At 6 you basically get a
when you ult.
When pulling off crazy Riven plays - Make sure to AA in between Q's. That's right, Q-AA-Q-AA-Q-AA-W-AA. Try timing your sheild to absorb the full impact of a lane's ability. by doing this, you reduce the amount of potential damage they can do.
Try charging Qx2 and flashing on someone low, AA-W to surprise them/deal tons of damage. In almost every lane, I recommend rushing
because everything in it is amazing on Riven. If, however, you are in a hard lane/falling behind. Go double or even triple doran blade.
Try to pick your trades well. If you can't trade, try to sit back and wait for 6 or wait till they mess up.
I hope this helps!