Originally Posted by Mizuen
e first, then w, and q at 8/9
EDIT: grab a point in e first then max w
I saw this quite a large number of times before I saw it explained: Taking E at level 1 is about the Explosive shot damage - 110 damage at level 1 is a lot at that level. Sivir, Ashe and Caitlyn can get that high provided they hit you and not minions and Vayne can do 90 damage if she can pin you to something (and the extra shot will definitely put her ahead).
Kog and Corki are closer to half that damage on their nukes.
So the theory is that with good positioning, e lets you do more damage in an exchange than any other carry at level 1, letting you be aggressive from the start.
W is obviously about the escape. You might get value from jumping on people in a level 1 fight, but your team would probably have to win the fight first to stop you from just dying.