Here's a self-portrait of me wearing a Crown (...Brand. I've not become royalty, ...yet.) that illustrates the orientation you're after.

Even though you can't see the way the neck-frame extends around to also hook over the left ear, it'll give you a pretty good idea of how to set the armature...

...HOWEVER...

Unlike this particular model, nearly all other headset mics work best with their booms retracted so that the mic capsule (or "head") is located roughly a quarter-inch (3-4mm) back towards the earlobe, away from (but in line with and pointing towards) the corner of the mouth. 

(By the way, it isn't actually a requirement that only dummies like me work in pro audio. Nevertheless, being a dummy often helps.)