Originally Posted by Coyote!
2. As huhenio says, give 'em the voice. . ."Go Home", "No", or my favorite "I ***** Bigger'n You". It's gotta' be at a deep and powerful tembre like you mean business. Limit eye contact, but make sure your body language doesn't telegraph fear.
I have to agree from results with the word "No!". Of course you have to say it fearlessly; but the word "No!" has one powerful difference from the other expressions. Virtually every dog understands "No!" and understands it the way you mean it.
The others may or may not be in the dog's vocabulary. For example, your last exclaimation. Our dogs would pick up on the "S" word which to them is associated with the "***** Kit" we use to pick up their remains when on a walk, and thus when they hear the "S" word, they assume that they are about to go on a walk.