I agree on the pet food. The cheap corned based stuff doesn't save you money. Your animals just eat a lot trying to get enough nutrition and poop a lot. It also leads to high vet bills as your pet ages. I feed my cats taste of the wild. I grumble every time I buy a bag because it is almost thirty dollars, but I have a twenty one year old cat and a fourteen year old that are both pretty darn healthy. We also have a two year old that supplements his diet with mice and he is a solid ball of muscle.
Thrift stores can be a great place to shop, but you have to know your brands and regular prices. Sometimes they are priced more used than you could have bought new. Certain brands also last longer so know who makes what. Example...faded glory is from
Walmart. South pole is from jc penny. The south pole brand clothing is sturdy as all get out and will last for years. Faded glory, not so much.
Garage sales have the best prices for used stuff. It can be harder to find good items though. Get to know where there are large community organized garage sales so you can save on driving around. There are a couple in my town organized by the HOAs and the people in those communities can only have a garage sale on that specific day. Those are great.
Flea markets used to be a good deal, but now everything seems to be cheap stuff from china and not average joes selling extra stuff. I might go once a year.
Farmers markets can be a good money saver. Again, you have to know the typical prices for different foods. Most times the farmers markets do have a better price, but not always. Out here, the price for peaches at the farmers market is always higher, but the farmers market price for peppers is way lower.
Garden if you can. Even if you don't have a lot of space, an herb garden can save you a bunch of money. thyme, chives, sage, mint, etc... Are all super easy to grow.
As for coupons, I only use then for cleaning supplies or toothpaste, etc... If you are buying food with coupons, you are most likely getting NON food disguised as food. Processed cereals are the worst. They are nothing but carbs and fillers. Eating cereal adds to weight gain and actually robs your body of nutrition. Eat eggs instead.
If you are building up a food storage stash, fill it with beans, lentils and peas. Also add dried veggies, lard, olive oil, butter, dried fruit, nuts, and very nutrient dense seeds like quinoa, amaranth, and chia. I also have a stash of spices I can't grow myself, coconut milk, canned tomatoes, and canned meats like tuna and chicken.