What's the best way to maintain the fuel efficiency of a Nissan X-Trail?

I recently bought a Nissan X-Trail and I noticed that the fuel efficiency is not as good as it used to be. What can I do to maintain its fuel efficiency?

Regularly check and replace the air filter to improve air flow and combustion efficiency.

Make sure to use the recommended grade of engine oil and change it according to the recommended schedule.

Avoid aggressive driving and try to maintain a steady speed to reduce fuel consumption.