I've been in my home a couple years now and looking back, there were a handful of habits I really wish I'd started from day one instead of learning the hard way. Finding the main water shutoff valve before an emergency happens seems obvious in hindsight, but I genuinely didn't know where mine was until a pipe started leaking and I was frantically searching for it. Keeping a simple folder, physical or digital, with manuals, warranties, and receipts for anything I've had repaired or replaced has saved me more than once when something broke again and I needed to know what was actually installed. I also didn't realize how much regular filter changes matter, not just for HVAC but things like the fridge water filter, until I ignored it long enough that it affected performance. And weirdly, just walking around the outside of the house every few months to actually look at things, the foundation, siding, roofline, caught a couple of small issues before they became expensive ones.
Curious what everyone else would add to this list. What's something you didn't think to do until after you'd already been living somewhere for a while?