First you need to make sure your furnace and AC are properly sized, running and configured to deliver the proper CFM to each room in your home.
Second, you need to make sure your filter is changed regularly (every 3 to 4 months) and that it is not restricting airflow.
Third, make sure your duct dampers are properly set. these would need to be set seasonally for max comfort.
Four, make sure your duct system is not blocked. if you have never cleaned your duct, it is strongly recommended you get your ducts cleaned.
now properly balancing your duct system takes time assuming the above 4 checks have been done.
ASE offers an onsite service package for $99 plus applicable taxes which include checking the 4 key areas listed above, that is currently creating hot and cold spots in your home. Click here to get more details.