Twisted Fate is often seen as one of the most powerful midlane heroes in the league, his long range and mana regeneration allow him to harass without needing a great amount of potions. Start in the middle lane, throwing out cards at enemy champions as much as possible, at level 2 focus on hitting mana cards and alternating once you reach 75% mana. Throughout the game you are capable of dealing a large amount of damage and ganking with ease.
In order to gank properly put yourself in a position that is almost out of range of your teleport target, then TP to a bush behind the enemy. From here you can destroy them without the fear of them running too far off.

In the midgame towers are incredibly important, arrange with your team to be doing something different to them. If they are defending then you should attack, taking advantage of your teleport. If they are attacking then you should slowly push lanes, staying in range of your towers should you need to teleport and protect them. This will allow for a fast farm, while still benefitting your team. By this stage your auto attack should be sufficient to kill champions at a fast rate, while your long range Q can be used as a finisher to hit fleeing enemies. Do not be afraid to spam your abilities, but always make sure you have enough mana left to use your shuffle, as a yellow card can be a handy escape, while a blue will help your regeneration.

By now you should be farmed, don't forget to use your items, but the game should be pretty easy from now on.