Hi :)
This is my very first guide so please dont be to rude :)
This guide is made for normal mode games and should teach the common fiora player who to play her toplane.
Im bringing you this guide because she recently got a minor but in my opinion unnecessary buff. I think she was OP before the patch and now she's just even more devastating. Her power lies in her great early game against squishies and generally all melee top champs. If played right you can easily get a kill at level 3 and snowball your lane, even the game. But you have to be very careful lategame because in that point, she becomes almost useless when outplayed. But lets get started..

Pretty standard as you can see. I wont go in detail here because theres nothing to say actually. You can maybe change the red / guints to all arp or all ad. This mixture here lets you farm PERFECT under the tower at early levels. meleeminion: 2 towershots + 1 hit = profit, casterminion: 1 towershot + 1 hit = profit. Very useful if your enemy's a ranged and you cant farm.

Some people believe Fiora can be played as a offtank. I have to say NO. It just doesnt fit her. You need to rape their carrys faster than they can rape your teammates (or you). This way you need loads of ad, high crits and lifesteal. Nuff said.

Now this is important, i didnt write this guide to show the reader which items they should buy or what items are the best. Its all about opinons. I just tell you why i get which items in which circumstances.

Standard build (VS most champions)
Berserker's Greaves Standard AD Carry Item
Rush this thing for more needed mobility and AS. I once used to play Fiora with Ninja Tabi or Mercury's Treads but its just not worth it if youre playing glass cannon.

Zeal -> Phantom Dancer Optimal AS Item for Fiora
Getting Zeal early is vital for a good earlygame. Your Enemys will walk away from you since youre fiora. This item helps to catch up to them, provide some excellent AS and a bit of crit, useful when you got IE. Get Phantom Dancer after IE so you profit from the critchance.

Infinity Edge Main source of Damage
In the moment you get this lovely thing, your enemies will fear you even more. Squishies will begin to cry you a river if they didnt begin before.

Bloodthirster Lifesteal <3
If youre getting outsustained top, get this item before IE because it gives you nice AD and Lifesteal.

Guardian Angel "KILL HER, ok she's dead. she returns KILL HER, **** ulti WHERE IS SHE OUCH OUCH" you have slain an enemy.
I hope you got this. Burst the enemy, if you cant kill him with ulti before you die, safe it. After your return your enemies will cluster around you to focus you down asap, best time for your ulti bro!

Optional / situational item
Maw of Malmortius GA combo :D
Get this in addition with some life ( Frozen Mallet or banshees veil maybe) against fed AP carrys. If you get revived by GA and use ulti, you will deal even more damage with it and lifesteal yourself up. Profit.

Executioner's Calling F*ck you Dr. Mundo, Warwick, Fiddlesticks, Volibear...
I always get this item if there is a fed champ with insane lifereg spells. Leave out BT for it. It provides you even some crit that fits your IE. Sometimes i even get this item just after zeal because it will make your top enemy cry when they pop their lifereg spells :)

Quicksilver Sash Underrated item
Facing a hard cc champs top like Warwick or Malzahar? Get this item! Its not that expensive and really saves your *** through the whole game. Also nice to break debuffs like Mordekaiser's ulti or Amumu's Ulti. This is a very nice item but you have to get used to it, otherwise its whorthless.

Madred's Bloodrazor Shredding tanks all day
Personally i dont like this item. Maybe its because in most normal games even the offtanks go squishy and this item is just not worth it then. In addition your target are the squishies and they rarely buy much defense. But if their most fed champs are tanky as hell, get it. But notice that you should have some defenses too because you profit the best of this item if youre fighting for a while.

Flash Ignite

The best for her imo. It fits her playstyle very good. Sometimes you need that flash for a close escape or to catch up for being able to Lunge to your victims. Ignite is doing very well on her because she can use it in ulti, giving some extra damage that your enemy cant avoid while you avoid almost everything.

Optional Summoner Spells and my opinions to them

Personally i think you should always pick Flash. Period.

Heal Doesnt fit her as strong as Ignite imo because you need to make as much damage in a short time and having Ignite instead gives you a spell with which you can finish off people from distance. Heal will be useless too often because if your outnumbered or outplayed as a Fiora youre f*cked. That little bunch of life wont save you.

Exhaust Actually a good replacement for Ignite. Can get you the upperhand against guys like Tryndamere, Olaf or Darius. But i prefer Ignite because it shuts down those op heal champs that you face top very often.

Teleport I like this spell very much. You can make soo devastating moves with this if your bot lane is warding. If your whole team doenst have one, you can think about this.

The rest is unmentionable i guess.

EARLYGAME

Buy boots 3 pots and if there's no invade or no need for helping your jungler, chillax at the base for the 4th pot. It will help A LOT if you cant snowball your lane from early on.

Now go in lane, lasthitting and stuff... I TOLD YOU TO LASTHIT !! most fioras just push their wave from early on, endangering theirselves by early ganks and long escapes. Its important that you dont push in the first levels.

LEVEL UP get that Lunge! now its time for some trade. If your fighting a melee (even Olaf), Lunge on him and autoattack. Now its important to look what your enemy does.
"oh he's turning around, walking to the tower" Q AGAIN, AUTOATTACK AND GO BACK TO THE MINIONS.
"oh he activates some fancy stuff / stabs his sword into my face" IMMEDIATELY ACTIVATE Riposte AND AUTOATTACK. Lunge again for extra damage. he will either die fighting or walk / flash to his tower.

you should be winning the trade no matter what.

LEVEL UP get that Burst of Speed! so your enemy is on 50% life, near the minions and you already have flash and ignite? dafuq?! if you cant q on him, Flash -> Lunge -> Burst of Speed (-> Riposte if he fights) -> Lunge -> Ignite -> profit.

you maybe think "duuude fiora is stronk but not THAT STRONK" you maybe are right. I completely disregard the enemys abilitys to either close gaps, stun, taunt etc. But this playstyle is for the general enemys. Ill do some matchups later and of course keep this guide updated. Its important that you avoid all sources of poke damage / avoidable damage but meanwhile lasthit dat minions.

To help your team a bit more and your wave is pushed too hard, go either kill the enemy mid or steal the red/blue buff. Sometimes i even chill at the buff till the enemy jungler comes and kill him. Its mostly very unsuspected in normal games and very efficient but keep your eyes on the enemy mid and your top enemy. When one of them go ss, better get the hell out of there if youre not fed.

You now should have got a kill. Lasthit some minions if you need more gold and head back. You MUST buy Berserker's Greaves, 2 wards and at least 2 pots and/or a Vampiric Scepter.

Now keep harassing your enemy with Lunge -> Burst of Speed. On level 6 you can easily towerdive your enemy with Blade Waltz which got buffed. Its Cooldown has been reduced (yay more QQ) :)

If you realize that their jungler is babysitting your lane, keep calm and KEEP HARASSING. you heard right, Lunge the nearest champ, activate Burst of Speed and Riposte (best used for dodging onhit abilitys like jax's Empower or nasus Siphoning Strike) and Lunge on an enemy minion to GTFO. Rinse and repeat. if they are low enough, use the second Lunge for damage and activate Blade Waltz for those lovely double kills. SNOWBALL-TIME.

On your second trip back, you should get a Zeal and Wards. If you dont have a Vampiric Scepterand you have the money, get it.

You may ask yourself "BRO why dont you get sum AD??" Its quite easy, your Riposte satisfies you with enough AD so you can focus on more Attackspeed and both Zeal as Berserker's Greaves give you more AS AND more movespeed, which is quite devastating for getting kills (you dont say?).

Get on the lane. do the lasthits. Keep your river warded / watch out for ganks. Deny your enemy / rape your enemy.

MIDGAME

By now, you should have crushed the enemy tower and you can rooooaaaaam like a boss. Focus on the lane, thats doing the worst. Mid is quite easy to kill because there are the squishies and most of them dont ward. dont be afraid to towerdive AFTER they used their abiliys. If you cant close up to your enemy, use Blade Waltz. Profit.

Stick together with your team. Go ganking. DONT BE THE INITATOR. Seriously I cant stress enough on this. There have been so many times where I yelled at my mointor (its fine, just played too much olaf), blaming myself for being so aggressive. When you start the fight, you can fight for around 2 seconds, then some CC breaks in upon your head and you die. CC just breaks Fiora so hard. You cant do much after being CC'd then maybe pop your ult and if youre lucky jump on one enemy. Then youre getting focused again and you die.

So this tip here should be FOR EVERYONE because i saw it so many times in normal games. burn this sentence into your brain: DONT. CHASE. TANKS.
seriously dafuq?! following scenery: me (fiora), random tards (some lame champ composition) and on the enemy team a shen. Shen walks to our red. my team attacks him (legit, he's in our jungle, we were 3 guys and some enemy champions were spotted bot). my team chases him. and chases moar. until their blue. shen walks to the blue brush with 30% life. my whole team is bunched together in front of this brush. anyone feel the magic? SHEN TAUNTS TWO OF MY TEAM WITH HIS DASH, THE WHOLE ENEMY TEAM BURSTS OUT OF THIS BRUSH AND KILLS MY CHASING TEAMMATES. Seriously remember this sentence. dont chase tanks. fine thing in early game but not in mid. period.

LATEGAME

Again, stick together with your team. Secure the objectives. If no one wards, do it by yourself. At least always have a ward on baron, dragon and between wraiths and baron (you know that spot at the wraiths on baron's site..c'mon). Focus their most fed SQUISHIE! even if their garen is the most fed, focus the squishies because there's no sense that you focus a tank (I assume their garen isnt going glass cannon.. nevermind).

If you see, there is a teamfight going on soon, ward some brushes near you and hide! Let them think you arent there so they are like "hey guys, their carry is base, lets get them!" WRONG! when the tf starts, come from behind or jump out of a brush and kill their carrys. If played right you can kill a carry in a few seconds and if they dont have an escape mechanism, they are *****d.

Now either you killed the enemy's carry, you failed killing her or he killed you (FAIL! but possible).

in the first two cases the whole enemy team will turn to you, trieing to kill you so youre instict after killing or failing the carry should be, GTFO !!! because you used your burst, your gapcloser and your riposte which lets you very vulnerable and outpositioned mostly. run away.

If one catches you, flash.

if they still catch you, fight for your life and only pop your ult if you guardian angel isnt ready. Still focus their carrys.

Maybe you die. After dieing, position yourself near a enemy squishy, activate Blade Waltz Pretty nasty combo with a Maw of Malmortius.

Ill do a few now and keep this section updated if my guide gets enough views.

Olaf Level: hard
My main :) Seriously this guy can bring every fiora into a world of hurt. If he's a ****** and maxes Undertow first, you can easily win. Just dodge the axe and dont let him pick it up again.

If he maxes Reckless Swing first, your *****d. The only way to beat him, is to get an early advantage, like kill him on level 3. After that, deny him to farm. This sounds silly, because hes Reckless Swing will do insane damage so he should win trades but the key is to trade with him long enough. His most damage only comes from this spell so you have to do more damage in those around 7 seconds he has it on cooldown.

Singed Level: easy
You have to shut down singed right from level one on. if he wants minions, hit him. again. again. kill. the rest is easy. Singed is extremely weak in this early levels. Just dont chase him when he has mana..

Jax Level: mid
To win against this guy, you have to play very concentrated. Because both champs can counter the other. Your Riposte is the counter to his Empower and his Counter Strike is the counter to your ulti. So use Riposte to avoid Empower and wait for his Counter Strike before your do Blade Waltz. You outdamage him. Abuse it.

EARLY GAME
Get lasthits
harass
dont be afraid to towerdive with ult
ward
keep your eyes open for ganks and counterganks

MIDGAME
play in team for ganks and towers
avoid tanks
dont get outpositioned

LATEGAME
play in team for objectives
focus the carrys
play as a ghost

and the most important: DONT. CHASE. TANKS.

I know this Guide is quite bad formatted. Wall of text incoming and stuff but i dont want to waste my time doing a beautiful guide which is downvoted for other reasons.

Please Vote with some feedback so i'll keep it updated and insert some more match-ups.

Fiora

10.7.2012 created Guide
11.7.2012 Updated Summoner Spells, Detailed Item suggestions; to be continued