Twisted Fate is an extraordinary champion who can be very viable with either an AD or AP setup.
Sadly, it has come to my attention that, while many excellent AP TF (Twisted Fate) guides exist, there are nearly no good AD Twisted Fate guides.

An AD build has come to my attention that compares with no other. One that is sure to boost your elo quite a lot if you play your cards right (pun totally intended ;D ).

-Greater Marks of Desolation: More armor pen = more damage. Best choice.

-Greater Seals of Vitality: TF has shorter range so he really needs to get in there. Health per level helps him stay in longer and keeps you alive if the assassin makes it to you.
Why not mana regen? Your "W" give you mana!! You'd be an idiot.
Tip: If you don't have Seals of Vitality, just use flat armor ones.

-Greater Glyph of Shielding: After laning phase you'll be seeing a lot more of the AP carry. These glyphs will add a butt load to your survivability.

-Greater Quintessence of Desolation: Again, more armor pen = more damage.

Typical Ad range carry mastery page. 21 in offence for more damage and 9 in defense for more survivability.

Heads up: Unless it will counter an opposing champion (Teemo's blind for example), sell Sword of the Divine late game and buy a last whisper. Sword of the Divine is just amazing on TF for the moneyyou put in to it. Your 2k will give you amazing attack speed and an active and will give you nearly true damage early game. After everyone has their items it's a different story. SotD becomes stupid and you need a last whisper, so get it.

-Starting:
Go Dorans Blade if you have a good support, if you think you'll be out-laned then go boots + 3 health pots.

If you chose Dorans then buy boots, if u bought boots then skip this.

If you're farming well or getting fed then go straight to a B.F. Sword. If not, buy up to three Dorans Blades (depending on how many you feed you need).

After this, continue with the build.

-Additional items:

You can switch the Banshees Veil out with a Black Cleaver for more damage.

If you feel you're just getting focused down every team fight it's usually bad positioning, but if you can't fix that then grab a Frozen Mallet somewhere in there.

Against 4-5 AD champions consider Ninja Tabi.

If you're against alot of Brusers and Tanks with high hitpoints go with a Maldreads Bloodrazor instead of the Phantom Dancer; this will also allow for an early baron (if you have an IE, maldreads and someone to help tank baron then you can get it).

If you don't think they'll be building physical defense then you can skip the sword of the divine. Grab just a Zeal or the recurve bow before finishing the IE, depending if you plan on building Maldreads or or a Phantom Dancer.

Max your E for it's passive.

Grab w second because it gives you endless mana, a stun and a AOE slow.

4get Q because it's stupid on AD TF.

Take R when you can.

I take flash as a must on TF. He is squishy and needs an escape someone trys to assassinate him.

Exhaust is a great summoner spell when it comes to exchanging with the opposing AD Carry. It also helps secure kills, gives an extra slow and shuts down that annoying trynd who is always diving through your team to try 3-hitting you.

If you're against a lot of CC then Cleanse is a MUST for Twisted Fate. Trade Exhaust out for this. Also consider if your team has enough Exhausts already.

-Other Viable Summoners: Ghost, Teleport, Ignite, Heal (when the troll in solo Que decides you need a second AD carry bot....) and Surge.

Get every last hit possible, don't take unnecessary damage, stay with the team and KS everything you possible can until you trust your team mate. Take red buff every chance too, TF is a beast with red:)

Consider AP Twisted Fate if you're done picking and have no mid.

Use your Ultimate to help your team see ganks, using the teleport with it is not a must.

Teleport with your Ult to save towers, stun under the turret if you're tower dived..if a fed garen is coming at you before your Sword of the Divine is complete just stun and run.

Pros:
-You can mystify your opponents by magically seeing their whereabouts.
-Great for cleaning up after a fight.
-Nice CC for an AD carry (an AOE slow + a stun).
-Endless mana if you're not stupid.
-Scales insanely well into late game.
-All the ladies love his goatee. ;)

Cons:
-Insanely squishy. A Frozen Mallet should fix this.
-Short range, even with the recent buff.
-Can't take being tower dived very well.
-Needs good farm.
-Picking cards are sometimes a pain.

Never do this. His ganks are nice if you're their level..but you'll just end up feeding the jungle monsters. Sorry :S

This is just a basic guide to playing Twisted Fate as an AD carry. Twisted Fate is a very hard champ to learn because of how different he is, but if you follow this guide and play TF way too much then you'll be in love. Who knows? maybe you'll be playing with Reginald and Dyrus soon :D