Dorans first then if you have enough gold you either get boots or a B.F Sword.
If your not doing too well then you might want to get boots and Vampiric sceptor and work your way up. then build yourself a Runaan's Hurricane because it really helps with farming and increases your attack speed significantly. Thing is about Twisted fate is that you have to avoid damage in early game so if you get your wild cards first you can stay a bit back and still finish off minions and harass. If you get hit and don't have a healing support well then your stuck with that damage until you go back. So i recommend buying a few health potions. Mana isn't exactly a problem as long and you know how to use your Blue card.This build is a late game build and focuses mainly on your farming ability. If you cant farm. Well then there's runaans hurricane to help you. Plus the extra 2 "Attacks" from it boosts your stacked deck as well. Frozen Mallet because well why not. Extra health and your cards slow when you attack.
If you find yourself being aimed down like instantly.Then buy a Guardian Angel ASAP. If you cant even land your stun then something is wrong and you need more survivability. Even with the frozen mallet.Infinity Blade is just for more damage and the extra crit chance simple.Last whisper is because many tanks snowball and are impossible to kill late game. With it you can take down tanks and tanky damage in a few shots.

First off you want to tell your support to get crowd control skills or healing skills. For example if your laning with sona then tell her to get her heal.If your support has a stun of some sort tell him to get that. If you have 2 stuns then your gonna pretty much dominate bot lane. stun one guy then stun the other and they both cant do anything. Late Game you want to use your ulti to the fullest.
You see your team engage then teleport to the back lines and kill off the damage. Don't worry even if you die your team should be able to handle a tank or 2. Damage is gone so your job is done. Twisted fate also has a very good chance to backdoor. If you can you save your ulti and walk up to the tower. If you see that they notice you just ulti away. or if their distracted by your team then use your ulti and teleport to a tower and take it down. usually the enemy team notices and chases you. Thus saving your team if they are losing. Always remember who your fighting.However since you got dorans ring you can have a better chance to kill anyone with a blind cause your ability's are resistant to blind. Exhaust is for damage that you cant control. For example if you see 2 dps next to each other you stun one and you exhaust the other. Then you kill off one and then your stun is back on cd you stun again and ta da 2 assassinations.

If your just beginning to play Twisted fate. I recommend going into a practice match and testing this out first.You have to first learn how to pick out cards right.I you cant pull a stun out of your *** ASAP then it usually means A:You dont get a kill or B:You die.Learn the cards and try a real game ONLY when you feel confident.

1:Harrass with wild cards
2:Stun with gold card or Harrass with Blue Card
3:After stun throw another wild cards and attempt to make sure you hit him/her
4:Stacked Deck should proc by now.
5:If he/she gets away and is vulnerable ulti away and finish it.

Pros
You can rock the game.
Late game is amazing.
Many ways to harass.
Your an assassin so you take out DPS very quickly.
If you fight against another adc you will probably win because most adcs don't have a stun like yours.They might have a blind or knockback like draven or a slow but rarely a stun.
If you play your cards right you will almost NEVER run out of mana. Blue Card.
Cons
Many people may call you a troll and make fun of you
Alot of people don't like ADC TF and may get a bit "angry" when they see it.
If you can get good with this i'm sure you can prove him/her wrong.
If you don't land ANY of your skills then your pretty much screwed
You rely on mana. No mana, no stun, no ulti and nothing happens except stacked deck.
Early game is a bit slow.
Very squishy and can't regen health in the beginning.

So This is my guide on TF. I dont like playing him as an AP cause if he has no mana he cant do a thing. literally. All of your damage relies on mana if your AP and if your AD you can take out people very quickly. I've been called a troll,loser and etc. but i almost always turn out with a good score. People don't see the potential of TF. If you get fed you can take out whole lanes in less then 10 seconds. The bonus gold is good too especially if your good at farming and getting Runaan's makes it even better.
Good Luck on the Fields of Justice everyone :)