Hi, this is my first build on mobafire. I thought I would shear my riven build as it has worked really well for me.
Play very aggressive early game, try to get first blood, you will have the advantage in early game combat if they have only got boots and pots (no stupid level 1 dives though). Also be a **** and don't let them farm, go in on them if they are about to last hit, but forget to farm yourself.
When the their jungler comes to gank remember your CC. You could probably get a kill on top lane and get out of there before getting killed yourself. If anyone dives you use your stun and dash out of there.

Build them in the order on screen but try to get the avarice blade (it builds into the atma's) early as it gives you money.
Remember the passive on the maw means you will have an extra 60 AD when you are at half health and even more if you have less than half.
Sell you starter item whenever you are very close to affording something big but it would be too long to wait for.