How can I improve the gas mileage in my Toyota Yaris?

I recently purchased a Toyota Yaris and I'm a bit disappointed with the gas mileage. What can I do to improve it?

Make sure your tires are properly inflated - underinflated tires can lower gas mileage by up to 0.3 percent.

Limit your use of the air conditioning - using the air conditioner can reduce gas mileage by up to 20 percent.

Reduce excess weight in your car - every 100 pounds of extra weight can reduce fuel economy by up to 2 percent.

Follow the recommended maintenance schedule - regularly changing the oil, air filters, and spark plugs can improve gas mileage.