A slogan should be positive, like an exhortation

A slogan should be positive, like an exhortation.

"Do good to those who oppose you" is positive.
"Love one another."
"Be of good cheer!"
"Service with a Smile "

Parents, teachers, Masters, best exemplify and exhort positively. Mainly because, if you tell the Pupils, students, young'n's, "Don't {x}!" what do they hear? "{x}!"

Don't is a good reminder once one has learned Do.

So, Do No Evil® tells you right away....