Every few months these coupons show up in the newspaper that offer $10 off a $50 grocery purchase. They never have a very long shelf life (like four days) so I always clip them and run. The trick is to use them for staples, other items already offered on sale, to target spending at exactly $50 to maximize the savings percentage, and purchase only food items. This coupon comes from Safeway and is valid if you also have a club card.
We used the coupon to stock up on dog and cat kibble (we like to keep at least one extra bag of each as part of our emergency supplies.) Threw in 2-for-1 18 count eggs on sale (hey, when teen-agers are running through at all hours of the day or night, lots of eggs are required), bread, pasta, milk, OJ, some fresh produce and such. We did exceed our $50 by about $6, paying $46 for the whole load.
These types of coupons make it worthwhile to clip and use them. While I see lots of postings about others clipping coupons and finding lots of deals in their Sunday newspapers, I honestly am usually disappointed with the offerings. All I ever seem to see are coupons for hair coloring products, expensive disposable razors, or Captain Crunch cereal. When I do see a coupon for a product we actually use, it's dismal: .30 cents off two jars of salsa or something. Not many coupons for avocados, cantaloupe or milk in our hometown Sunday paper.