This document provides 10 tips for parents on various risky behaviors in tweens and teens, including substance use. It notes that parents are the number one influence in a teen's life. The prefrontal cortex, which governs impulse control and decision making, is not fully developed until the early 20s. As such, early substance use can lead to problems with addiction later in life. The document recommends that parents monitor their teens, communicate clear expectations, and intervene if they see warning signs of risky behavior.