How can I improve the fuel efficiency of my Ford Focus?

I purchased a Ford Focus a few months ago and I have noticed that it's not getting as many miles per gallon as advertised. Is there anything I can do to improve the fuel efficiency of my car?

One way to improve fuel efficiency is to make sure your tires are properly inflated. Underinflated tires can decrease gas mileage by up to 0.2% for every 1 psi drop in pressure.

Another tip is to avoid aggressive driving and sudden accelerations. These actions use up more fuel and can decrease fuel efficiency.