Here is a guide to Twitch by WoWGametron.

Summary of Twitch
Skill order
First 4 levels = E-Q-E-W
After 4 = R-E-Q-W

Item Build
Core
Doran’s Blade
Emblem of Valor
Berserker’s Greaves/Mercury Treads
Avarice Blade
Infinity Edge
Stark’s Fervor

Thanks WoWGametron!