tldr: Being mindful and trying to find new ways of using stuff that I already have before I go buy new.

I reuse. All those bigly plastic bags from 20+ toilet paper rolls - I use them at least as thrash bags. That's like simplest one, but also for example when my clothes are beyond being deemed worthy of being sleepwear, they get cut into cloths to live on as cleaning utensils.

When something breaks I tend to try to repair it instead of getting new stuff. If that's impractical or not possible, depending on a thing I disassemble it, and salvage what can be useful. Also by doing this I learn how stuff was made, which I liked to know since being a kid :)

I found europalletes and repurposed them to make my balcony space nicer (made flooring and a small bench out of them) I also ask people if they have spare construction materials, like bits of wood or stuff like that. There are fb neighbour groups in my area, and it makes so much sense to me to use what I can get in my projects. I rarely have a full-on plan/vision of the stuff I want to make. I much rather have a storage with random materials and stuff and play adult version of Lego with them.

When faced with obsolete electronics, I try to repurpose it and assimilate into little Borg of mine (how I like to call my little network). I learned java a bit to write small android app to decode amiibo NFC data to control the stuff around my flat when phone (placed under the tabletop) detected Pikachu statue my lights toggled. Such stuff.

I dunno if with me it's less about saving and more about how to use things in different way and getting most out of stuff. A chipped cup can still be an awesome pot for your new plant friend. Broken cutlery knife can be helpful as a tool when you wouldn't want to use proper knife.

That said. When I have to buy something, like hobby-related, or electronics so guitar, piano, home recording studio shit like that, also PC parts - I set myself a budget, read upon things available, do my research and order stuff for 110% of my initial budget. What I mean by this, we have a saying in polish - chytry dwa razy traci - sly/greedy loses twice - as in you buy cheap shit, it breaks, you have to buy new thing again. When I set on buying something it will take me months to do my homework, and also because of my upbringing, lessens the anxiety from spending money.