Clean or replace furnace filters once a month (or as needed) with a filter that has a MERV 11 rating or higher.
Ensure that your HVAC system is properly sized for your home.
At the beginning of cooler or warmer weather have a professional come out to inspect your HVAC system.
Have your duct system checked for air leaks and proper insulation.
Consider installing a “whole house fan” to improve circulation and ventilation throughout your home.
Do not use humidifiers or evaporator (“swamp”) coolers with the air conditioner.
Close vents in unused rooms.