1) Get comfortable with a summer house temperature of 82-86 degrees F., and a winter temperature of 64 - 68 degrees F, so you need less heating and cooling altogether. (Hot baths or showers can help, or you can warm and cool the body with exercise.)
2) Use an intelligent combination of fans and a dehumidifier and opening and closing windows, as needed.
3) Replace your lawn with a thick layer of mulch that holds moisture. Grow appropriate trees around the house for shade. A friend of mine did this here in Florida and needs no AC in the summer, and rarely heat in the winter.
4) Use LED light bulbs to reduce electrical consumption and heat output. Control and turn off appliances appropriately.
5) Add additional insulation under your roof.
6) Choose an appropriate color for your roof - white for cool, dark to bring in heat.