One of the simplest, and potentially money-saving things you can do is to know certain crucial details about your house's major systems. A small problem can rapidly expand into a big emergency if you don't know how to mitigate the damage fast, and problems of any sort are more complicated and more expensive if you can't help with the trouble-shooting and solution.
Water can wreck your house pretty darn fast. The most important thing to know is where the main water shut-off is located in your house. Military families that move every few years may not always have thorough turnovers. Everyone who lives in your house needs to know where to find the main water shut-off and how to operate it. Don't be like me, having your kids sop up water while you run around the neighborhood to people with the same floor plan until you find someone home to show you where the water line comes into your house.
While you're locating your main water line, also find the shut-offs for any outside lines that may need to be drained to prevent freezing in the winter.
If your sewer backs up, you want to know a couple of pieces of information. First, what is the relationship with the county? For example, at my house, there is a cleanout at the property line. Anything between the cleanout and the house is my responsibility, anything beyond the clean out is the county's responsibility. In a back-up, the first thing I do is call the county, who will send someone out to verify that the problem isn't in their part of the line. Second, your house probably has at least one, and maybe a couple, of sewer cleanouts inside the house. Sometimes they're hiding, behind drywall or in a weird space. Then, depending on the length of your sewer line, you may have cleanouts in the yard. Knowing where all your cleanouts are located can save a lot of time and money during a sewer emergency. (Says the lady who has spent 6 of the last 24 hours looking for a lost cleanout in her yard.)
If your house uses natural gas, you have two main issues. The first is knowing how to turn off the gas. There are tons of tutorials on the internet, but I would prefer that you spend the money to have a qualified professional teach you. You don't want to mess with gas! In addition to the main gas shut-off, each individual gas appliance should have some sort of valve to turn off the gas to that particular object.
The second item is your gas meter vent. Houses with exterior meters have a vent as part of the unit. If your meter is inside, there is a vent that leaves the house nearby. These vents must be kept clear and free of debris, ice, snow, mulch, aggressive shrubbery, and toys of small children.
Depending on the type of system, your heating unit may have one or more emergency cut-off switches. I have seen them located near bedrooms, often up high, and sometimes there is also a switch on the furnace or boiler itself. If your heating or air conditioning is not functioning, checking these switches is a fast and free first step in trouble-shooting.
Also, some systems use air filters that require regular cleaning or replacement. You should know where your filter is located, whether it is cleanable or must be replaced, and how often that should be done. A dirty air filter will make a HVAC system work harder and can even cause them to stop working all together.
Lastly, most heating systems have some sort of vent. It may go through the roof, or be vented out of the side of the house. Side vents are susceptible to blockage from ice, snow, mulch, plantings, etc. Knowing where your vent is located is the first step in ensuring that it remains clear.
Take some time this weekend to locate these important fixtures. Consider labeling them, and ensure that anyone who is old enough to be home alone knows where they are located and how to use them. (Except gas, if you're not comfortable. You can always just leave and call the professionals.) Eventually, all houses have water or sewer or gas or heat issues, and being prepared will make the solutions faster and less expensive.