Treat pot lightly. "It's only marijuana" is how some parents think, says Levy. Be careful not to condone use in any way. No reefer jokes with a friend that your teen might overhear. "Kids definitely pick up on that message," says Levy.
Underestimate your power. "The No. 1 thing that teens say—and they're not going to say this to their parents—when they're asked, 'Why are you not using drugs? What's holding you back?' They say, ' 'Cause my parents expect me not to use them,' " says Williams. "That's the No. 1 reason. It's still parental expectation."