This is merely a build, I really recommend taking only the main points of this and building your own. Every game is situated differently, and there is no build that can beast every situation. Remember this before you start hating :3.

Twisted Fate is by far the most versatile champion in the League. Argue all you want. There is a certain catch to playing TF, you must play smartly at all times, NO MATTER HOW FED YOU ARE. If you don't and get cocky, you might start 11/0/5 and end up 12/13/7.

TF's based damage is horrible, no doubt, slow, weak basically not useful. You should try to last hit with blue card as it does 70+ damage instead of your lowly 50 ish damage. Also, when you're level 2 or lower, try hitting the enemy with blue card to slowly grind their health down.

By the time you hit level 3/4 you are ready for first blood, (hopefully no one's taken it yet...).
If you are mid, take their health lower than half, blue card, Q, run back, if they follow, gold card, flash Q, ignite. That should almost guarentee a kill.

Red card, nothing more to it.

Stay BACK. Do not jump in to the middle of a team fight, instead stay behind you're tanky teammates, gold/red card their ADC, Q and stacked deck. If you buy items correctly, you're Q & W CD's every 3.86 seconds. Remeber, no matter how fed you are, you'll still loose against tankier champs.

By mid-late game, you're deadliest weapon is not you're Q but W. Stacked AD and AP damage combines into a deadly arsenal.

Your ultimate. This is by far the most important part of Twisted Fate. There are many tips and tricks, but not one single trick will work for all situations. They include: On the champ, ahead of the champ's vison, inside a brush, way ahead of a champ inside a brush etc etc. This isn't something that I can guide you with, you'll have to develop it yourself. Remember, pracrice makes (almost) perfect.