Asklemmy

Rice or pasta with cheap sauce and some grinded meat can sustain a person for quite a long time.

When you cut veggies those cuttings can be a broth base, which you can refrigerate as ice cubes if you boil down water content enough.

Research 2-3 meals that are easy for you to make and are tasty so that it becomes fun to cook.

If you put drop or two less of washing detergent you still will have clean clothes, so it can stretch that bottle for one or two more washings.

Cloths have natural progression from wearable outside, then wearable in home, then it becomes either cut to wiping clothes for cleaning or cover for dogs bed. I learned some rudimentary mending to be able to fix small holes or fix stretch bands in sweatpants and such.
Socks, once other one from the pair goes to Narnia, go to cleaning utensils pile.

Finding way to repurpose, reuse or upcycle stuff can save up some money.
Learning basic maintenance, and how to fix stuff song the house can save up a good bit of money, and with internet it's easy to learn.

Trying to get most of usability and life from devices is important to get right mindset. Don't consume, use brain, utilize stuff that you already have, realize that serotonin from experience of buying stuff is temporary and hollow in opposition to enjoying making things happen with limited resources.

Beginning of this year i went thru my subscriptions and cut out nearly everything.

Before going shopping i make a list of things to buy, so that i stay on track and try to speedrun whole shop thing. I rarely buy snacks and unnecessary shit now thanks to that

Being frugal for me means cutting costs of stuff that doesn't matter to me so that i can achieve my goals and splurge on experiences and things i want. Having a goal that you want to achieve helps a lot. I ask myself "is X going to help me with my goal of Y" or "is X more important than my goal Y". It helps with finding strenght to be assertive.