AP TF does reasonoble damage start game but many other characters can counter him during this time. Champions that have a constant attack will make TF struggle alot start game, this includes champions like Cassiopia,Karthus and many more.Altough if he gets a kill,he'll practiclly be invincible because he will farm up and keep killing the opposite champion.
One fault about Tf is that at end game he is easily countered by other champions. His shining times are start game and mid game.

Skills affects
Wild Cards:Throws three cards in a cone shape.(Very strong for AP build).

Pick A Card:3 types of card effects,spellvamp,slow,stun.(Strong for both AD and AP).

Stacked Deck:Does magic damage every 4th hit.(Good for AS/AP together).

Destiny:Teleport a far distance on the part of the map.(Uses no stats but good for ganking or finding characters)

Laning reccomendations

I reccomend for you to go middle lane because its is easier to hit your "wild cards".
They're more visible so your "wild cards" and "pick a card" will be much more affective in middle lane.Although he is viable other lanes,just not as affective.

How to harass
To harass you must keep getting blue on your "pick a card" and keep hitting an enemy champion. When you get level 2,harass with "wild cards". If you keep doing this you'll eventually get level 6 and your enemys health will be at least 2-3 bars. Use your super (destiny) behind your enemy,this means turret dive and attack with "wild cards".

This strategy should work pretty good. If not post a comment and I'll change it straight away.

How to build
First get doran ring,get your boots,farm up and get boots of mobility.After this you should get a blasting rod to go on to your rabadon to deal alot more damage. Get a lichbane for your card stacking.A void staff would be a great item because if you get many kills,the opponents tank will get magic resist so it pierce they're magic resist.If you get far enough in the game get a rylais for survival and ROA (rod of ages) for more MP and HP.
(Sell dorans ring when you get to void staff)