IMHO, the real key to saving big bucks on groceries is a stock pile. I am not talking a giant disaster prepper stock pile (but if you want to go there, go for it!) but a modest stock pile. You create the stock pile by purchasing basic items you use often when they are at the rock bottom prices.
Kristin at Couponingtodisney does a great job of explaining how to do this.
I love weusecoupons.com as a great place to find weekly coupon matchups. They list each grocery store so you can find what you can get cheap or free each week with coupons, and they id the good deals without coupons, too.
Another key is to find a store that accepts competitor's coupons. My local Harris - Teeter takes coupons from Giant, Safeway, Wegmans, Shoprite, Shoppers, Target, CVS and Rite Aid. SO this week I used a shoprite coupon to get 4lbs of navel oranges for 99 cents (otherwise would have been 4.99), a wegmans coupon for a free head of lettuce, a shoprite coupon for a pineapple for 1.49 (would have been 4.49) sparkle paper towels for 3.99 with a giant coupon.... and so you see that I can get the loss leaders from multiple stores in one trip and save big money and save time, too.
buy toothpaste, toothbrushes, floss, shampoo, conditioner, deodorant, lotions, meds and so on at the drugstore where they put them on deep discount. they are way more expensive at the grocery store