Hi I am a random riven main. This is my first guide created. If anything can be improved, plz tell me.

Tanky Riven build:

Pros:
Tanky
Pretty good damage late game

Cons:
Less damage than normal build
Physical

Early: Do not rush too much since you build tank instead of attack damage.
If you win your lane
try to stop your lane opponent from getting and gold or maybe even kill them more times. Or you can help other lane win. If your losing your lane
play safe and try to get help from your jg and mid. Dont rush for minions last hit cause that might get you kill one more times. Try to help other lane if you can.

Mid:
Gank other lane and dont sit around in your lane.
Split push when your team is taking objectives. Try to bait the enermy's core champion so your team have more chance of win 4v4 teamfights
If your team are wining: use this chance and try to end the game as fast as possible. If your enermy is fully defend the mahor lane, dont waste time on that lane, push other lane or take objective
If your team as losing: Try to 1+ vs 1 your enermy and take imnortant objectives or prevent your enermy from taking it.
Play safe untill you and your team have item balanced with your enermy.
Dont teamfight if you cant win

Late:
(Include the guide from mid game)
Group together and try to win teamfight

Extra:
Try to cc the hole enermy in teamfights

Basic
Fast combo: AA-q-move click-AA-q-move click-AA-q-move click
Double cast: E-(two abilty or item active)
All in- e-r-w-(fast combo)-R

Normal
1: e-r-w-aa-q-a-r-q
2: (q-q)e-r-flash-q-aa-w-r
3:(with hydra) e-r-h-w-aa-q-aa-r-q

Adcanced
1: R-e-r-f-q-w
2:e-r-f-w-aa-q-aa-q-aa-r-q

There is still many combo you can do....

Sanstain-Tanky build
Damage-Normal build (about 100dmg per hit difference)
CD reduct-Normal build (10-20% defference)
In-game: 65% Tanky build won
Combo deffecult: Nether

After all, I would recomment tanky build for the one who's new too riven but advance riven can also play this build well.