If you are dealing with an aggressive driver, make sure your doors are locked. If you're stopped in traffic, leave enough room to pull out from behind the car you're following. If an aggressive driver confronts you, dial 911.
Be polite and courteous, even if the other driver isn't. Avoid any conflict if possible. If another driver challenges you, take a deep breath and move out of the way. Never underestimate the other driver's capacity for causing mayhem.
Allow plenty of time for a trip and listen to soothing music when you drive. Make sure your seat position and climate are comfortable for you. The best thing you can do is understand that you cannot control traffic, only your reaction to it. In the end, you may find that personal frustration, anger and impatience are the real danger zones on the highway.
Some states have a phone number that you can use to report dangerous driving to the appropriate law enforcement agency. Keep the number handy on your cell phone. If you make a call, be sure to give a vehicle description, license number, location and travel direction. You could prevent a tragedy.
You can set a good example, especially if you have children or young adults in the car with you. They will learn to mirror your behavior.