Tips for anything are a dime a dozen. This tip is no different, except that it can save that dime over and over again.
If you have an older duct system in your home, chances are the joints of the trunk duct and pipe aren't sealed properly. This can make your heating and cooling systems run less than efficient over the long run. Costing you money.
The good news is that simple things can be done to help the efficiency of your heating and air conditioning system. One of the most important is the previously mentioned, sealing of the duct joints. This is an extremely cost effective way to save on heating cooling costs over time. Plus, it's an easy job for anyone and can be accomplished in a relatively short amount of time.
First, I am providing a PDF link for the recommended best practices when sealing your ductwork. The document provides a great overview of the process and reasons for sealing your heating and air conditioning systems. Pictures accompany much of the descriptions for a better understanding of what is being explained.