Almost everything in your house has a manual. The furnace, the ac, the water heater, the water softener, the coffee maker, the fridge... they all have manuals. If the people before you weren't responsible and you don't have a packet of manuals somewhere, go through everything and download them. They all say exactly how to do maintenance for each thing, and how often.

Other than that it's mostly looking around and making sure nothing is actively being eaten. Take a flashlight and look around in the attic and basement or crawl space or whatever your can't normally see and make sure things aren't moldy or rotting. If you catch things earlier it's always cheaper and easier.

That's a rough one. I know a good place to start is anything large you buy, make sure you read the maintenance portion of the manual and make a couple notes.

Then I start asking myself about important things like "how do I make sure the plumbing doesn't get fucked? " or "how do I make sure the furnace doesn't die?" and I start googling.

Not a great answer but it helps. I recently realized I didn't give much of a thought to well pump maintenance and I've been down a massive rabbit hole on that one. I feel like you just pick one thing at a time and work on it and you learn as you go.

It took us years to compile the list and it’s paid for itself many times over.

But to jump start the list in a future place, especially a traditional house, I’ve considered hiring a housing inspector or general contractor to give us a walkthrough of key maintenance timelines. Many things could be decades away but easy to forget until it’s a much bigger job. Notes from that interaction would essentially be the bones of “the list.”

Just follow Martha Stewart's website, you'll find there are several thousand hours worth of chores you should be doing weekly!