One thing that we found really helps is that when we get a 'windfall' (tax return, bonus at work, etc.), we stock up on staples. There were years when we couldn't do that (because windfalls had to cover debts--thank god we owe for nothing but our house now), and it could be really hard. Even when you're a good cook and make just about everything from scratch, there's a big difference money wise between a 5 lb bag of flour every week or so at $3.50 a bag and being able to buy a 25 lb bag of flour for $9, and it lasts a lot longer. Can't remember who it was who said, "It costs a lot to be poor."
If you have staples that you just have to buy every few months, it's much easier to spend your weekly money on fresh food. We have big buckets (food storage type) for flour, sugar, and rice (which we buy 25 lbs at a time), and twice a year at case lot sale time buy a case or two of canned beans, canned diced tomatoes, tomato sauce, and tomato paste. With staples, there are quite a few things that can be made if you're tapped out on cash. Coupons don't do much for me, because I don't think there is a big enough taste difference on most things (with exceptions: mayonnaise, miracle whip, Clorox bleach, maybe a few others) to pay for a premium name. Store brands or bulk are fine
Like
staropeace said, though, not everyone has transportation to get large quantities home. Sucks. I often wish we lived in Star Trek: The Next Generation-land, where if you need it a computer just spits it out for you.