I haven't really done all that much of spending money to save money in the long run. For a long time we were financially right on the edge anyway, and it is only in the last 3 years or so that we haven't had the extreme money worries we used to have. Mainly because our now adult dc are working.
So basically I have resurrected old shopping habits, buying the cheapest cuts of meat, fruit and veg that's on offer that week, counting the number of apples in a bag and working out the cost per apple for instance, and checking the price per kilo of absolutely everything. I have also gone back to visiting the supermarket at the time of day when they put out their reduced stuff.
We have old cars, and despite increased maintenance costs, they are still cheaper to run than if we replaced them with newer ones.
We are lucky that we don't have any loan or credit card repayments, and DH only uses his credit card for one-off big purchases like a replacement washing machine, so we get the extra consumer protection that offers. His card gets paid off in full every month. I don't have one.
The only other thing I can really think of is that I am also now an enthusiastic switcher-off of lights that other people have left on in the house!
My parents lived through WW2 so make-do-and-mend was something I grew up with, and my late DM's favourite saying was 'Look after the pennies and the pounds will look after themselves'.