Automobiles;
Use less fuel:
Avoid unnecessary braking and acceleration.
Keep your tires properly inflated.
Remove extra weight from the car.
When doing errands, try to combine them to reduce your driving.
Avoid getting stuck in traffic.
Cruise control.
Use less air conditioning.
Buy used ~ Buy Hybrid or electric vehicles
Walking ~ Biking;
Walk or bike within 2 miles of home
Walk or bike to public transit
Promotes health
Trains and Subways;
Less air pollution
Less emission per person because it is shared
Develops electric transport systems.
Less production embedded than individual cars
Promotes community
Planes;
Avoid flying
Flying contributes about 2% of the world's global carbon emissions plus the infrastructure embedded in the industry
Also:
Fly nonstop
Fly less
Fly shorter distances
Fly economy class.