Clean or change all the filters in your house regularly, particularly those for your furnace, air conditioner or portable air cleaner.
Adjust your humidity levels around 45%. Anything under 30% is too dry, over 50% is too high
Stay away from synthetic air fresheners
Use a HEPA air purifier. Make sure to get an air purifier that does not produce ozone, and one that does eliminate VOCs that off-gas from paint, furniture, and cleaning chemicals