Replace Air Filters
Replace the return air filters every month.
Have a professional inspect the air conditioning and heating system once a year.
Adjust airflow at registers (floor or ceiling vents) to balance room temperatures.
Have your furnace tuned up every fall. Regular maintenance can prolong its life and alert you to any potential issues. Have it cleaned, lubricated, and adjusted before each heating season.
Often utility companies or furnace manufacturers will offer free or discounted inspections. However, these needed to be booked in advance as the slots fill quickly.