Start Boots and 3 Health potions, this gives you alot of mobility and easy to escape ganks with the help of your level 2 Shunpo, grab an Revolver, Early Negatron cloak, this helps you mitigate some of your opponents damage, pick up boots 2 then finish for abbysal, then continue to follow the item build and finally turn your revolver into a gunblade then Get GA , Dont let them focus you and act like a ninja !

Remember Kata should be played really Docile at first, let them poke you, let them think they have the upperhand, get your jungler to gank pretty early on and camp your lane pre 8, you will get fed, with the flash shunpo combination youll be able to close any gaps and do "tonnes of Damage" Then at 8, constantly roam and gank bot lane, be very aggressive, you can afford to turret dive them with your E Q W and E out Combo after kill or assist.

Think about it , Kata is an Burst assassin !

Pick them off one by one, refresh your CD's Burst the Squishies from behind, drop your ult after all their CC is used, you will not be dissapointed as they cant stop your burst like crazy and after you get a kill when they focus you, shunpo away, Q W and run ! Then re-engage when youve poked them down enough !

Classic Examples of this are done when i am streaming! :
http://www.twitch.tv/fallenfaith

1: ALWAYS FOLLOW YOUR LANE
if your opponent moves, follow them they gank top, you then either make the choice, follow them or gank bot, They go SS you go SS, You help your lanes
2: BE A BASTARD !
Seriously i cannot stress this enough, play mindgames with your opponent ! Let them think they can beat you burn Flashes and Ignites then bam, turn the tide burst and kill. Its that easy !
3: Dont be afraid to Burn your flash to Secure kills!

And please, help me by watching my stream !
http://www.twitch.tv/fallenfaith