All your flex water lines (the lines that go from the wall to the toilet/sink/washer/ect…). If they are over 5 years old, replace them. If they are plastic, replace them. Also, the shutoff wall shutoff valve: DO NOT trust it. They often snap off and create an instant full pressure fountain that will flood everything. Find out where your street side and property front shutoff valve are, and memorize their location. You will eventually use them for who knows what reason.
Do not underestimate the damage these flex lines can cause. Every single damn person I know that has owned a home for any amount of time has had one of these break, and if they are lucky, it is while they are home and only minor flood damage occurs. Often times it is when you are asleep or away at work, and it floods the floor with a few inches of water. This often results in a BARE MINIMUM of $20k + in damages!
This is often the most overlooked thing people ever think about, and is often one of the most devastating, ESPECIALLY in a home older than 25 years old. The reason? Asbestos. Virtually every older home has it, and when it floods, inspectors literally have to lab test your insulation for how much (because it WILL have some) is in there. If it exceeds a certain amount (which a home built in the 40’s absolutely will), the home is literally put under quarantine (read: $$$) until repairs can be properly done. Plumbing is no joke, and I would go so far as to say the most neglected and destructive thing in home ownership.
Oh, water heater tanks die after 5-10 years, so figure on replacing that soon. If you have a septic system, have that inspected. 40’s homes often have funky electrical systems, so don’t overtax it and learn what kind of fuse system it is running: You will open it up semi-regularly, especially on older homes. Yard work is a bitch, so learn to love it or pay someone.
As far some non-plumbing advice:
-Get some sort of tool chest. It can be the absolutely shitty $100 Harbor Freight garbage. What matters is that it gives you a place to properly store basic tools. When tools are easy to get to, you are more inclined to use them and get shit done.
-Get a CORDED drill. Makita, Dewalt, and Bosch are all good choices for something inexpensive and that will last. You will be surprised how useful it will be. Wireless is great if you use it a lot, but if you don’t, batteries fail, while a corded one will always be there ready to use.
-Screwdrivers, pipe wrench, crescent wrench, Knipex Cobra Pliers, tape measure, bubble level (get a good metal one!), utility knife, hammer, putty knife, punches combination square, serrated jaws pliers, wire stripper, hex key set, lots of high-amp extension cords, a ladder, and some good flash lights. With this, you will be able to take care of 90% of anything that goes wrong.
-Introduce yourself to your neighbors. They are going to be a great asset, or a great annoyance. You might as well try and get on people’s good side.
-Get a spare key and hide it somewhere outside that isn’t completely obvious.
-Ask your neighbors for advice on the area: good places to eat, things you should watch out for, ect.