Lets go.

Mark/Quintessence of Desolation: Very good ArP for the beginning, makes ur work easier in mid.
Seal of Resilience: Good armor with masteries.
Glyph of Warding: Good magic res with masteries.

The build order is fix. Infinity Edge building order is the following: If you have enough gold, buy B. F. Sword, else u might buy the Cloak and the Pickaxe first, then sell Doran's blade upon reaching 2k health.

I use Ghost and Exhaust instead of Flash and Ghost, which makes early game very easy to land a killing bow. Try it:D

Upon reaching level 8-9, i go and kill 1 of the golems and 1 of the lizards ( to get blue and red buff)
After that, start ganking lanes.

There's only 1 rule: W8 for ur team to engage, then do ur skills.

In this build U'll crit very hard coz of the infinity edge and the 300+ AD.