Your grocery bill is likely one of the largest parts of your living expenses. If you were to rank them from largest to smallest, it would probably fall just after mortgage (or rent), energy and car payments. You can't do much to lower a mortgage payment or car payment, so trimming as much as you can from your weekly food bill makes a lot of sense.

The problem is that we have seen food prices skyrocket, about as much as fuel prices over the past year, and it's taking an ever bigger bite out of our budgets. Here are some supermarket savings tips I've collected over the years of raising a family of four on a single income. Don't fret, they should work regardless of the number of mouths you feed or the income you have.

Know the numbers: Much of our supermarket spending is influenced by sneaky marketing tactics. But you most likely already knew that. The good news is that if you arm yourself with the facts, you can shield yourself and nullify these tactics. Comparison shop, so you know you're getting the best price. Don't buy everything at one store. Most locations have at least 2 or 3 supermarkets clustered within half a mile of each other. Pick the 2 that most constantly have low prices or the best sales on the items you buy. Once you have your target destinations, make sure you make heavy use of coupons and buy expensive items when they're on sale.

Speaking of sales, make sure it really is a sale. Do the math. If you need to buy 2 items to get 1 free, it's only a sale if you can use all 3. Another marketing trick is the incredible shrinking portion size. This is a relatively new phenomenon, caused by the recent return of inflation. Food producers are facing a dilemma: do they pass along the increased cost of production, or cut costs? Many companies are opting for the latter. The result is you pay the same price for that half gallon of ice-cream, only now it's not quite a half gallon anymore.

Know the system: Be prepared and have a plan. Make a list and stick to it. That way you maintain control, and don't fall into the impulsive shopper traps. Most grocery stores charge more for items that aren't on sale, hoping to lure you in with the sale items and make up the difference on the non-sale items. These sale items are known as “loss leaders” in the biz because the store often loses money on them in the hopes it will lead you to spend more on the non-sale items.

Loss leaders are your friend. Take the store up on their loss (sale items), but don't follow their lead and buy the higher priced non-sale items. Wait and buy non-sale items at other stores where the price is better. Once you know you about this trick, you'll make out like Bonnie and Clyde (except you probably won't get shot by a Texas posse).

Buy right: The cheapest price isn't always the lowest. You read right. Sometimes you think you're doing the right thing by comparing 2 similar items, and buying the one with the lowest price. But it's not the price that matters for some items – it's the price per unit. This is usually displayed on the shelf above or below the item, right next to the total price. The unit price is like a price per volume, and it's helpful in deciphering the best price for items from cereal to potato salad. Unit price is particularly obvious when comparing the brand name product to the store brand (generic) product. Buy generic when you can for most items. Substituting store brand antacids for Tums, probably won't make a difference but you'll spend a lot less. Some things however just don't work as generic. Mayonnaise comes to mind – there is just no substitute for Hellman's.

Don't overlook the basics: You've read them before, but they bear repeating: Never shop hungry and stock up on non-perishables when they're on sale. You can save a bundle on stock piling non-perishables. I constantly tease my wife about having enough shampoo to last until the next millennium, but she's constantly getting them buy 1, get 1 free and using a coupon to boot. The result is 2 bottles of shampoo for about 75% of the cost of 1 bottle.

Do your homework: Another great way to save on groceries is to plan a menu of meals for the week based on the items on sale that week. For example, if chicken breasts are on sale, plan a meal around chicken breasts. This is especially effective when you can apply coupons toward the sale items. But your homework goes beyond menu planning. Keep a price book. A price book is simply a list of common items you buy and the average price of those items at 2 -3 grocery stores you frequent. This way, if you are tempted to buy something that is not on sale, you can do quick look-up in your price book to see if it's still a good price or if you can get it cheaper at another store.

Use the corner store: I know some people say you should avoid the corner store, and this is largely true, but if they have a better price for staples like milk or bread – go for it. For example, Stewart's is a regional convenience store where I live. There's a Stewart's on just about every corner and they consistently have the best price on milk. Not only that – their milk is produced on local farms and is constantly voted the best milk in the state by the leading university of agriculture. Buying milk from Stewart's also supports the local farm community. Couple that with a milk club card, which gets you a half-priced gallon of milk for every 5 you buy, and you'd be a fool to pass this by.

My wife and I have managed to feed our family of four on just a little over $110 per week using these tips. Well, OK I admit: it's really my wife. But I am very appreciative of her hard work and concerted effort in keeping the food costs to a minimum.

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