This guide is written only as a point of reference for myself for my particular Fiora build that seems to work for me.

Pros:
- E provides most of the attack speed, so you can focus on damage items
- High DPS mid/late game
- Easy early-game kills
- Good early-game sustain passive
- Good ganker
- Hard to lose a kill when you can chase with Q
- Once committed within a 1v1 battle, extremely high odds of getting the kill

Cons:
- Any CC will shut down Fiora effectively
- Slightly squishy early/mid game
- Item dependent for damage

Exhaust Flash

Replace Exhaust with Heal or Ignite depending on how you play.

Promote is also an option if you feel you will be pushing towers a lot.

Vampiric Scepter is bought first as it works extremely well while laning, especially with your passive sustain, and given you put a point into Riposte, the passive attack buff from that should be enough for early game. Boots is next for the move speed.

Wriggle's Lantern is acquired next for it's unique passive (helps with creep farming) as well as warding your lane to prevent any incoming ganks. Mercury's Treads is bought next to lessen the effects of CC. B. F. Sword to boost your damage up a bit more - At this point you should be able to get some kills, and you will definitely be getting some kills when you get your Infinity Edge.

Phage, followed by Frozen Mallet is bought next for it's unique passive slow ability, on top of the extra HP you receive from Frozen Mallet.

Madred's Bloodrazor takes advantage of Burst of Speed, allowing you to rack up additional damage against tanks.
If there aren't really any tanks, Last Whisper can replace this item.

Sell off the Wriggle's Lantern when you are close to having enough gold and buy Bloodthirster for it's extra damage.

Lastly, finish off with Guardian Angel for the armour and revive.

Some people like to incorporate Tiamat into the build to take advantage of the on-hit splash damage from Blade Waltz, if this type of build interest you, then you can replace Madred's Bloodrazor and Guardian Angel for Tiamat