Twisted Fate is one of my favorite champions. He can slow, stun, and even regenerate his mana through one of his regular abilities that has a low cooldown. He also, if built right, can rip a tank apart with nothing but a gold card and his melee moves! Oh, and let's not forget his ultimate... which we'll go into later...

Pros
Can Shred a tank apart when built.
Great harasser.
Ultimate lets him help in so many ways.
Great for ganks.
Can get away most of the time.

Cons
Squishy.
Casters can kill him if they know how, but they're also squishy, if you get the jump they're your's.

Before getting into much, here's a quick look at TF's abilites.

Wild Cards - This is a joke basically, I don't even learn till forced to. Cap Pick A Card and Stacked Deck first, then Destiny, then this.

Pick A Card - LOVE THIS. I'll explain the different cards...
~Blue Card - Gives you the ability to not have to recall for mana. Great for harassing for it does the most base damage.
~Red Card - Good base damage, and is AOE, so you can go through minions quicker with it. It's also a slow, but I don't really use it for that purpose. I use the stun.
~GOLD CARD - Whenever fighting or chasing, use it. It stuns, letting you hurt them even more.

Stacked Deck - I cap this and Pick A Card at about the same time. Within a level or two. Passive, it gives attack speed and cooldown reduction. Also, every fourth attack it deals even more magic. So, when harassing, get three hits on minons, then choose your blue card, and throw it at the enemy champion, you'd be amazed the damage it can do. Use one of the 3 cards on a fourth hit if possible.

Destiny - One of my favorite ultimates... you can teleport anywhere, thus giving you the power to rule a 3v3 map. When to use this you ask? 3 main times...
1. When they're running away from you, teleport in front of them with a gold card ready.

2. Help an ally or help out with a gank.

3. Defence, whey you die, you can teleport to your tower if under attack and quickly help it out.

In both of these, it's pretty straightforward, pick up some attack speed, damage, and a little bit of cooldown reduction.

My items are pretty I build for are for attack speed and damage mainly. Here is the order in which I get my items.

1. Bers. Greaves - Attack Speed, movement speed, ya know. You need boots.
2. Phantom Dancer - Attack Speed, and even more movement speed, for Twisted Fate is slow. Also, critical hits, they're very important to well... critically hit your enemies. For this, I get zeal first, then whatever I can afford first for the other two.
3. Infinity Edge - Attack Damage, Critical Strike Chance
4. Sword of the Divine - Attack Speed, every fourth hit hurts the target even more.
5. Either Bloodthirster, or the Black Cleaver. Black Cleaver will give even more attack speed and damage, but Twisted Fate is squishy, so if you Bloodthrister, you get life steal so you don't have to recall as often.
6. I usually just pick up a B.F. Sword. By this time you'll have more than enough attack speed, so just pick up some straight damage for the last one.

Twisted Fate really only has 2 useful abilities, and his ult, which is AWESOME. Anyway, You want to cap Pick a Card and Stacked Deck at about the same time. Wild Cards is the last thing you get. I don't even learn it till The other two or capped. So, here's your sequence to get that kill...
1. Use Destiny to teleport to them, to get the jump on them. Select your gold card before jumping into a fight.

2. GOLD CARDS!!!! I cannot stress this enough. It does the weakest base damage, but, it stuns them, letting you get the most damage including your auto attack hits.

3. That's about it, Stun, hit them, stun, hit them and repeat till they're dead. Use Exhaust or Ignite if they decide to run too much.

I only think 5 of them are very useful.

1. Ghost - Great for getting away or getting the kill that's running.

2. Exhaust - They're slowed, it basically makes them your's if used correctly.

3. Ignite - Gives that extra damage over time you may need if they do get away.

4. Flash - Like ghost, getting away and chasing down.

5. Heal - Need I say why?