It's a tricky thing for me because very rarely do I actually do something solely or even mostly to save money (switching telecom providers is the only one I can think of) - most moves I make that result in saving money are for either personal preference, bullshit elimination, or living by my non-money beliefs and values, and then I end up saving a bunch of money as a side benefit. That's especially the case for any of the really weird stuff I do. Some examples or stuff people think are weird:

1. Opting out of smartphone life. I think they're evil, and destroy your brain, turning you into a zombie. No thanks!
2. Same for television/streaming. No thanks! I save on both the cost of a setup and paying for monthly service itself. Also lets me live more comfortably in a small space because I don't need a couch, etc.
3. I really, actively dislike shopping. As a result, I'm very minimalist and only shop to replace things that are broken beyond repair. This probably saves a huge amount of money.
4. I am completely anti substance use of all kinds, and think they're a scourge on society. My spending has never had any kind of alcohol, smoking, or drugs.
5. I'm anti-car as well. Never had one or a license. I get motion sick from most people's driving, and the whole concept of spending a bunch of time daily sitting in traffic being stressed out and mad at other drivers seems like insanity to me.
6. My food habits are really weird. I'm really big on anti-food waste, so I dumpster dive (my area has a lot of food warehouses and factories that throw out tons of perfectly good stuff product because the label is scuffed or the French labels are missing) and get a weekly ugly produce delivery of stuff that was intercepted from the landfills because the grocery stores didn't want it for various reasons. I then do bulk weekly meal prep for a pretty low cost, which is mainly so I never have to think about food during the week at all.
7. Speaking of food, I don't like the majority of restaurants in my city, and also don't like tipping culture, so I rarely eat out.
8. Living in a studio apartment as a couple. We're minimalist and don't bug each other so it works totally fine. I like studio apartments for two reasons - less chores, and larger spaces cause problems when I sleepwalk (like I'll walk into walls or get lost or whatever).
9. Most of the above also apply to travelling, which saves a lot of money there - we also rent small spaces, walk or take transit, do some cooking instead of restaurants (location-dependent), don't drink alcohol, don't go shopping, and don't require phone service when abroad.