Check the outside clothes dryer exhaust vent periodically. If it doesn't close tightly, replace it with one that does to keep the outside air from leaking in. This will reduce heating and cooling bills.
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.