Here's my build order: boots and 3 pots - rush Tiamat for easy farming - i then get Wriggles Lantern because its amazing even if your not jungling - berserker greaves - build the tiamat into a Ravenous hydra - giants belt then build into warmogs - last whisper - bf sword and build into bloodthirster.
Life steal is very important on Fiora because you can 1v1 anyone, wriggles removes the need to buy wards, and ravenous hydras onhit works with her ult so I find this build to be amazing. i hope it works for you, gl hf.

Masteries, Runes, Summoners
14/13/0, ArmPen Marks / Armor Seals / MR Glyphs / ArmPen Quints, Ignite/Ghost

Skill Order
QWQE (ranged) / WQQE (melee), R > Q > E > W

Start Choices
Flask, Cloth Armor

Core Items
Blade of the Ruined King, Ravenous Hydra

Boot Choices
Mercury Treads, Ninja Tabi

Situational Supplemental Items
Brutalizer, Phage, Hexdrinker

Late Game Items
Black Cleaver, Last Whisper

Defensive Choices
Frozen Mallet, Guardian Angel, Mercurial Scimitar, Randuin's Omen, Maw of Malmortius

Most important things to work on are how and when to trade in the laning phase and how to team fight. Q combos (Q > auto > wait > Q > auto, QQ > auto, Q to creep > Q to target > auto) are incredibly important to master as well. When are going to attack a champion, make sure you have a stack of the passive as well as every little bit can help. This way you reach the Duelist cap faster. Practice makes perfect, and experience is what gives you the knowledge of whether you can trade or not successfully. She a lot better in trades then most realize right now. Team fights are effectively about assassinating the AD Carry or some other squishy high-value target. There can be some choice in determining whether to use E before or after a Blade Waltz, but in general you should start a team fight by coming in after the team fight has started (preferably from the sides) with an E -> Q -> W -> auto -> Q -> auto until low on health -> Blade Waltz -> activate items on last slash -> hopefully you can reactivate E now -> kill everyone. Obviously, not always going to happen, but it's a place to start.

Adapt your build to the game as well. What I wrote isn't always going to be true. If you need faster percentage penetration, then you need those items earlier. If your opponent is going to fight you melee all the time, then maxing E is probably your best bet. (Do not max W first unless you really know why you are doing it, in most cases melee stand-and-fight trades do better with E and ranged trades are far better with Q.) Adapt to the game. Change your runes to something defensive if your opponent is going to wreck you. Adapt, practice, and learn.

I go Flask+Ward/Pots
Get berserkers greaves,upgrade with furor later.
I always rush a hydra first unless im bot,then ill go bt
Level up r>w>e>e
First six levels are w,q,e,w,w,r
W makes it was easier to last hit,and helps against ranged champs,and melee ones.
Also if youre in mid and have good reflexes,this can output good damage if they try to passively harass you with aa's
Final build usually looks like
Ravenous hydra
Berserkers greaves with furor
Black cleaver
Last whisper
Blade of the ruined king
Phantom dancer/stattick shiv
Have fun with her,as she is a vastly underrated champion but a monster if you take time to learn her.

My limited experience with her is a bit different. I have found building her with on hit effects to be amazing. I disagree with hydra because it doesn't really help her farm better, just push lanes faster once you do win a duel.

I think BoRK and BC are her core items for me. Those two provide insane dps and sustain if you use your skills correctly.

After those it depends. Phage->FM isn't really necessary o find with her ability to stick to targets and gap close. But the burst potential of Trinity Force has merit perhaps.

I don't like building crit because I don't believe any of her skills apply it. Lifesteal from a BT is always welcome in a duelist build, and will process on some of her skills. I also really like wits end as a MR defensive item. Even though it applied MD and not AD, it is significant boost to her output nd applies both the MR buff and damage on her Ult.

Hope that helps...

Stay Rock Solid,
-gap81

My personal preferences:
Boots + 3 Pots> Brutalizer> Vamp. Scepter> Berserker's> Hydra> BC> Guardian's Angle> Scimitar> Last Whisper.

AD Reds
Armor Yellows
Mr/lvl Blues
Lifesteal Quints.

Specifically regarding the Hydra, it's not just for her to push lanes faster. It certainly gives her that option, but that's not the only reason. The reason you get Hydra on Fiora is a whole collective of reasons. The splash damage for farming, the splash damage for team fights, the massive increase to life steal recovery both after and during team fights, the active's burst damage (BotRK plus Hydra is devastating burst), and the item itself actually gives plenty of AD to supplement that. If you get a Hydra, you never need to get a Bloodthirster and in exchange you get a whole metric ton better at team fighting. If you think about it, Bloodthirster is a huge waste anyway since she gets over 400 AD with just 4 other AD items and she isn't really that good built with crit anymore.

I mean, the moment where I get BotRK and Tiamat alone is a huge turning point in my ability to carry games. The burst damage skyrockets. Normally these items paired together aren't capable of being utilized properly on most champions, but Fiora's kit provides extra advantages to these two items on top of their incredible burst synergy.

I would however never say to rush the Tiamat/Hydra. It's always a secondary item. I mean my most common path personally is Brutalizer, Blade of the Ruined King, and Hydra. Brutalizer early because I often win the lane due to opponents not understanding Fiora at all, but I don't upgrade it because early on it isn't going to be that great. BotRK to further dominate the lane and win any duels, and then Hydra to win team fights.

http://na.leagueoflegends.com/board/...ighlight=fiora

a very recent thread discussing fiora builds and options { my comments & builds are in the link}

im not going to copy paste the entire posts again when all u had to do was search