How do I improve the fuel efficiency in my Ford Focus?

I've noticed that my Ford Focus's fuel efficiency has been decreasing. I would like to know what steps I can take to improve it. What should I do?

I suggest checking your tire pressure regularly. Underinflated tires can decrease fuel efficiency.

Make sure to have your air filter checked and replaced if necessary. A dirty air filter can impact fuel economy.

Avoid unnecessary idling and use cruise control on long highway drives to save fuel.