I haven't been able to read everyone's responses, but one suggestion I have is to put less emphasis on specials and coupons, and rather than looking at the price tag, look at the price per unit on items. In my store it's the top left hand corner of the tag thingy they put on the shelves. Don't buy the package that costs the least, but the one that is priced lowest per pound or ounce or however it's being broken down on the tag. It will most likely be the more bulk item. Then be sure to control the desire at home to eat more because there is more. I've stopped buying the little 8 ounce (I think it's 8 ounces!) bars of cheese that I used to buy, but end up rather buying the big 2 pound blocks. Yes, I'm paying a lot more on that visit to the store, but then I'm not buying any cheese for a month or two, and overall, saving a lot of money. By shopping this way, I find that my grocery lists tend to only have about 7 or 8 items per week, rather than the old lists that contained 20 or 30 items, and ultimately, I'm spending a lot less. Also see if there's a food club or buying club in your area, where you can buy some seriouly bulk staples, like rice, pasta, lentils, cooking oils, etc. You can go online to find food clubs. Also, try cooking more from scratch. If you don't already, sit down for an hour and read about breadbaking and get started. I did and I no longer buy any bread products whatsoever. The "art" of breadbaking is really overblown, in my opinion. It just takes a few tries and you'll have it nailed!
Edited to say: Okay, I guess that's more than one suggestion!