Coupons are free money, but only if you use them for products you would have purchased anyway. Companies offer coupons because they want you to try their products, and they figure they'll give you a bonus for taking a risk, but this isn't how you save money on food.
Instead, as you peruse coupons, cut out only the ones for products you already use or products that you're willing to use because you're not loyal to another brand.
If, for example, you couldn't care less what kind of detergent you use, cut out all laundry coupons and use the ones that save you the most money. But if you never eat anything but Sugar Cereal for breakfast, don't cut out coupons for Fruity Cereal, no matter how much of a savings you'll get.
Even though cereal is considered a staple of the American diet, most cereal, with its refined flours and sugars, isn't really that good for you. And ounce for ounce, it's one of the most expensive foods in your grocery store. Eat more nutritionally dense food at breakfast, and you'll save money and still feel satisfied a few hours later.
Cutting out coupons is just the first step. To actually use them, you'll have to have them handy and organized.
One cheap, simple way to keep them accessible is to put them in a 3″ × 5″ card-file box, organized by category. File the coupons under their appropriate categories, placing them in order by expiration date, so that the coupon that will expire first is the one you see first when you flip to that category.
When you add new coupons, flip through each category to see whether you have any expired coupons that you need to toss out. Keep the box close to your keys so that you never forget to take it into the store with you. or, if you tend to forget it, keep it in your car.
Look for coupons in the Sunday paper, keeping in mind that coupons usually aren't offered the weekend of, or just before, a major holiday. Also, if you're buying the paper only for the coupons, make sure you're saving more than the cost of the paper each week.