Hot tubs and spas use a lot of energy. A lot. So think about whether you really need one in your life. If you do, take these two steps.
First, if you haven't installed it yet, make sure to insulate it well around both the bottom and the sides.
Second, make sure you cover your spa or hot tub with a tight-fitting, insulated cover. That is, when you are not actually in it. Then you can take the cover off.