Don't post inappropriate or sexually provocative pictures or comments. Things that seem funny or cool to you right now might not seem so cool years from now — or when a teacher, admissions officer, or potential employer sees them. A good rule of thumb is: if you'd feel weird if your grandmother, coach, or best friend's parents saw it, it's probably not a good thing to post. Even if it's on a private page, it could be hacked or copied and forwarded.