Make sure dryer vents and chimney flues are cleaned and maintained regularly (At least once per year, or more often depending on use). If your fireplace has an ash pit make sure it is cleaned out regularly and that it is sealed correctly. Check flues and connections of the furnace/ boiler/ water heater to make sure they are sealed properly and free of obstruction.
Check the batteries and replace them often (experts recommend they be checked once a month). I would like to recommend that you install hardwired-interconnected smoke detectors in all bedrooms, in halls outside of bedrooms, and at least one per floor. Experts recommend using heat detectors in certain places where smoke detectors might get fooled (such as kitchens, outside steamy showers and furnace rooms).
Carbon monoxide detectors
They should be placed on every floor of homes equipped with fuel burning appliances especially near sleeping areas. My understanding is that Carbon monoxide detectors only alarm when CO has reached dangerous levels. This may not inform you of a lower level contamination which can also be harmful over time. There are detectors on the market that have a continuous digital readout of CO parts per million. You may consider these for extra protection. One brand is Nighthawk Deluxe Carbon Monoxide Detectors BENHDELUX.
In addition to detection maintenance, survey your home for potentially dangerous situations like overloaded outlets, old or dusty electrical equipment (i.e. computers), old or improper electrical cords or extension cords, and cluttered, dusty furnace or laundry areas. Remedy these situations. Have a fire drill regularly, especially if you have children.
As houses are designed to be tighter and tighter sealed for heating and air-conditioning reasons and more combustion equipment is installed, you must have enough fresh air coming in the house to make up for the air leaving the house or negative pressure will develop. Negative pressure can potentially stall exhaust gases from properly leaving the house. Fireplaces, boilers, furnaces, dryers, and kitchen /bathroom exhausts all draw air from the house. When this equipment is in use it is important to allow fresh air to enter the house. The larger the house the more this comes into play. This could be done by
simply opening windows or by directly venting outside air into areas that need it.
Grading and drainage
In order to help keep basements and crawlspaces dry make sure the grade around the perimeter of your home drains away from the house. It is important to keep this in mind as you do your yearly landscaping and garden maintenance. Check and clean all gutters and downspouts and make sure they exit away from the house.
If you have a sump pump, check that it is working properly and that it has not met its life expectancy.
Radon gas tests
New Jersey has many radon areas; you should periodically test your home and check your radon systems.