Early game Attack Damage will allow you to be able to kill the enemy teams Champions early game, which will allow for faster item building. The Masteries give you Ignite +5 Attack while on Cooldown and gives your Teleport a faster Cooldown, which comes in handy.

If you have a jungler try to play mixed between Defensive and Offensive, catchinng you opponent off gaurd with a quick hit or 2 then E out. Once your opponents over extend try to go for the squishiest one first. Try to keep your Health above 50% unless your Ulti is up.

This build allows for some early game damage. The only negative part is you may find yourself overextending to get a quick kill, which will leave you open to ganks from an MIA or enemy jungler.

Flash - The reason Flash is an important part is because of the options it gives you, you can escape a gank by Flashing over a wall, or use it to get a last hit, or kill an opponent then Flash out of the Tower's range.
Ignite - Ignite is an overall useful spell early on, it will allow you to get a kill as you run from a fight, and with certain masteries, if its on CD you will gain bonus Attack and AP, which are helpful early on.
OTHER SPELLS
Exhaust - Exhaust can allow you to slow an enemy and quickly defeat them, or slow an enemy for a quick escape.
Surge - With Surge, you can get some Attack speed and Ability power, both being useful. AP for you Q and Attack speed to get rid of those nasty enemy Champions. Plus it makes you big and scary!