What is the most effective and safe method to prevent helmet visor fogging during cold weather or rainy riding conditions?

1. Wiping the inside of the visor with engine oil or brake fluid before departure
2. Holding one's breath continuously while navigating high-speed traffic
3. Completely taping shut all helmet air intake vents to trap warm breath inside
4. Installing a Pinlock dual-pane anti-fog insert lens and keeping helmet chin ventilation vents open