When installing in-wall speakers, use a drywall saw to cut the hole. A utility knife will make the cleanest cuts in drywall, but a utility knife can be difficult to control by a non-expert. Electric rotary saws make cutting drywall physically easy, but they too can be difficult to control. A simple, inexpensive drywall saw (about $10 at your local hardware store) is the best bet for beginners. The speaker's frame will cover up any rough edges.
Keep your furnace tuned and in top condition. Proper maintenance of your furnace can save 6 to 10 percent of your heating bill. Have a certified technician look at your furnace and make the necessary adjustments before the heating season starts.