What's the best way to maintain my Toyota Corolla's fuel efficiency?

I've noticed that my Toyota Corolla's fuel efficiency has been decreasing lately. What can I do to improve it? I don't want to spend too much money, but I also want to make sure my car is running at its best.

Regularly changing your air filter and keeping your tires inflated to the correct pressure can greatly improve your fuel efficiency.

Try using a fuel injector cleaner every few months to clean out any buildup in your fuel system.

In addition to regular maintenance, try to avoid sudden acceleration and braking. This can help improve your fuel efficiency.