In this build i tried give u my personal experience.
I dont want to bore u so i ll start it :D

1; For start u can buy a boot and 3 potion too . So farming with the minions and if the enemy have low health kill him. if u have money to the berserker go home immediately and buy it. So in this build there are 2 phantom and 2 infinity. It is because the crit. if u have got fullbuild u ll have got 110% crit chance and the crit deals 250% crit dmg. So if the enemy haven t got any armor you ll damage 600 to him/her. The sequence is all the same s your choice. And nastor s tooth. It s needed for the attack speed and the AP. If the enemy build to armor u should buy a Rabadon's.To the place of the first Phantom u Can buy a madred's too.
But if the enemy build to armor there is the second build :D.
2; In this build u start with an Ionian. The secund item is the malady. It give you 50% attack speed and 25 AP.The nastor's tooth is give 65 AP and 50% attack speed. so this item and the malady give +100%attack speed.It is give mana regen too.Archangel's staff : it is give manaregen and AP too .Thees re really important.The Triniti Force is the best item to hybrid AP/AD carry... And the Rabadon's is give you +140AP and it is increases your Ap with 30%.

http://www.youtube.com/watch?v=E2Bsosl3mm8
This is a nice example to the teamwork.
This character have got the longest range in the game.
so it is very good to gank.

In my build this Kog haven t got a lot of healt.
So for your safety buy wards.
Strongs: -Miss fortune - difficulty=4/10 - She is a good champ but not versus Kog....
-Kennen - difficulty=4/10 - He's biggest advantage is that he is very fast.U can slow him down and after execute him.
Weaknesses : -The strong AD characters for example Yi and Tryda in 1v1. try to stay away from them.