They say that lowering your thermostat by 2 degrees is supposed to save 4% (on average for 16 hours). It is also suggested to lower your thermostat at night by 5-10 degrees (depending upon where you start from during the day) to save 5-10% on your heating bill during that time. And if no one is in your home during the day, set your thermostat to a lower temperature during the day as well.
Invest in a programmable thermostat so that you can easily program it to change temperature on a schedule that works for you. There is no reason to heat your home so warm when you are not there, so set your thermostat to begin heating up the house before you normally get home so that you can enjoy the warmth, but not have to suffer with the cost of heating it to that temperature all day.
Also, remember to lower that temperature on your thermostat when you go on vacation. Set your thermostat to 55-60 degrees. You shouldn't go lower than that because you don't want your pipes to freeze. Plus, you have to consider the welfare of your pets. You decide how low is appropriate for your pets.
The formula to figure out how much money you will save is 1% for every 1-degree lowered for an 8-hour period. So, with knowing that formula, you can figure out when it is best for you to lower that thermostat. And if you are just starting off, start out slow and lower it 1-degree lower for a week and then lower it another degree for a week. It might be too much of a shock & discouraging if you try to lower it too much too fast. Most people will not notice 1-degree difference.