Put air conditioners and pool pumps where the noise won't annoy neighbours.
Use noisy items like lawn mowers only after 7am Saturdays and 8am Sundays and stop before 8pm on any day.
Had complaints from your neighbour about your dog barking incessantly? Ensure it has enough space to move freely in your enclosed yard. Don't leave it on a fixed chain for long periods and exercise your dog regularly.
Create a vegetable garden or plant a fruit tree with your children in your backyard or in a pot. More plants mean cleaner air and a reduced need to purchase pre-packaged / processed food.
In winter, woodheaters in Sydney can produce up to three times as much fine particle pollution as cars and trucks. To minimise smoke, use seasoned wood and give it enough air to burn properly - avoid the temptation to turn down the air flow late at night.