I think one of the best tips I can give you for saving energy on your cooling and heating costs is to invest in the most efficient HVAC system you can find. Get a reputable company to install it and get a good service plan from them and you will be set for years. I like to stick with the top name brands when it comes to HVAC equipment because they just run better and last longer than the cheaper no name brands. The efficiency is incredible nowadays with the latest equipment and my power bills are almost as low as my wifi bill each month. I would love to switch to a solar HVAC system one day once I feel that it is advanced enough to beat the electric system that I have in my house now. I know that they are always working to improve things in the field and can only imagine what they will be like in another twenty years or so. I may invest in a geothermal heat pump one day when my current heat pump is old and ready to be replaced, but I am pretty happy with how much, or how little, my power bills are during the winters. I also recommend having some type of dehumidifier in the house because lowering the humidity in the summers in the house can make you feel much cooler for much less. Installing ceiling fans in each room you frequent is another way to trim back on cooling costs. You could also get zoned heating and cooling like I have to avoid heating or cooling the whole house.