Alright, lemme introduce myself. My name is Tugisch & im playing League of Legends for 1 1/2 years now. My summoner name is GermanyL0L and I'm actually playing in the Eu-W server. At the moment I'm playing in Gold III division & try to climb & climb. You want to know how many games I've played with Kha'Zix ? Alright, I've played almost 400 ranked games with a win rate of 65%~ with Kha'Zix. Most of them played in the jungle!

Kha'Zix is my "main" champ ya know, playing him since release & resisted against the nerfs!
Well, you want to know how to play good as Kha'Zix ? ;) In this guide you may get a few helpful tips. I'm actually playing Kha'Zixa as jungler, but sometimes if jungle is not free I'd just like to play him on the Top/Mid-lane too!

+ YOU'RE A BADASS ASSASSIN
+ YOU'RE AN AMBUSH BUG :]
+ YOU CAN GET FED VERY FAST
+ THE SNOWBALL IS DESTROYING SO HARD
+ YOU DON'T NEED FLASH BECAUSE YOU HAVE BALLS OF STEAL
+ RENGAR IS A KITTY CAT AND BREAKFAST FOR US
+ NO CONS xD

Runes... I'm using a different rune set than others maybe. But it's actually good for me so...
Since you're an assassin you'll need some bursty damage in the early game.

Try that:

9x Greater Mark of Attack Damage!
9x Greater Seal of Attack Damage!
4x Greater Glyph of Attack Damage!
5x Greater Glyph of Armor!
3x Greater Quintessence of Armor Penetration!

I'm always going for 21/9 masteries, just because Kha is an assassin and needs the AD.

Early game: Build as much AD as you can and burst the enemies down!
Midgame: Build as much AD as you can and burst the enemies down!
Lategame: IF you have enough AD to burst your enemies down, start building tanky items.

ABILITY SKILL ORDER:
MAX W FIRST
MAX Q SECOND
MAX E LAST
Skill your R at Level 6/11/16

EVOLUTION:
EVOLVE Q FIRST
EVOLVE E SECOND
EVOLVE R THIRD
YOU CAN EVOLVE YOUR W INSTEAD OF R TOO IF YOU LIKE TO POKE YOUR ENEMIES.

Most of the time I run SMITE & IGNITE.
"But why IGNITE?! YOU NOOB ?! OMFG"
Of course mate, read, be surprised, change your opinion.

Since Kha'Zix is an assassin (xD) you'll need moar damage than any other champion in early game to get fast kills, alright ?;)
I'd take ignite because you will get an damage boost of 5 AD when you have ignited your enemy and hopefully killed him in early game! In early game it'S very useful!
Let's imagine you've ganked successfully early okay. You've got the kill and you got that 5 AD boost because of your 21/9/0 masteries, alright.
Just buy some ****ing AD with your gold. You cant imagine how much you are ahead in this moment. When you come to gank somebody on toplane/botlane, you would just rape their/his ***/es OK ? AND WHEN YOU ****ING MAX YOUR W FIRST YOU WOULD JUST DO SO MUCH ****ING DAMAGE & ****ING ****ING KILL THEM AND HEAL WITH YOUR W AND SURVIVE AND ****ING GET FED. BUY LAST WHISPER FIRST THEN BLOODTHIRSTER, WITHIN YO BUILD THESE, JUST THINK ABOUT BUYING SPIRIT OF THE ELDER LIZARD. IT's KINDA IMPORTANT BECAUSE OF THE COOOOLDOWN REDUCTION. BOOM IM OUT. :]
I'm editing this guide everyday soo, feel free to leave comments here. Ask me anything. I would answer them quickly & try to help you the best I can.

I'm streaming sometimes, you could add me ingame and see when my stream is online and when its offline!

If you have some wishes about putting a video to this guide or smthing else, like I said just feel free to leave a comment :>