Turn off lights when not in use. This sounds obvious, but many people have a habit of leaving light on as the go from room to room.
Unplug appliance and electronics when not in use. Many of them still draw electricity, even when turned off.
When possible, use a fan instead of your air conditioner.
To help with the above, use blinds on windows to block the the heat from sunlight in the summer.
Thaw frozen foods in the refrigerator before cooking. This will save from not using the microwave or extra cooking time.
Configure your computer for sleep or hibernate mode, or shut it off when not in use.
Don’t open the oven door if you can check through the window.
If you are making a smaller meal, use a toaster oven or slow cooker instead of a full size oven.
Keep the refrigerator at 2 degrees and the freezer at -18 degrees. While this will ensure food safety, lowering the temperatures further only wastes power.
Only wash full loads in your dishwasher. This will save electricity and water. Air drying the dishes will reduce the amount of energy used.