With gasoline at $4 a gallon and food prices on the rise, shoppers will do well to consider some basic rules for coping with inflation. It probably will be harder and harder to make ends meet, but care in grocery shopping can help cope with the economic squeeze.

First of all, watch out for snacks. Nutritious real food costs less in the long run than those expensive chips and cookies and sodas that may taste good but aren’t really satisfying.

A second rule: Keep in mind that you pay extra for cutting, slicing and fancy packaging. For example, bags of lettuce mix cost much more than a head of lettuce. And you pay extra for single servings, such as cereal in bowls.

Compare unit prices. Big packages can mean economy, but not always. You may be paying for empty space. Researchers have found that in a typical supermarket the larger size of a given brand is the poorer value 25 percent of the time. The Federal Trade Commission found that canned tuna, peanut butter, ketchup, canned coffee and frozen orange juice frequently were costlier in larger containers.

Eye-level shelving gives products a boost. Top and bottom shelves are “death rows” for slow-moving items, but also where you can find lower-priced store brands and things like less-sweet cereals. Sugary cereals are usually in middle shelves, where children are more likely to spot them.

Beware of checkout station temptations. A comparison shopper saw a cooler at a checkout counter offering 16-ounce bottles of juice for $1.19, while similar bottles shelved a few feet away were priced at 50 cents.

Evaluate “end caps,” the displays at supermarket aisle ends. Merchants have found that they can increase sales by a third, but don’t assume they’re on sale. Sometimes, however, you will find a bargain.

Colors can affect buying decisions. Experts have found that black suggests luxury, while bright yellow means no-frills and inexpensive. Green, of course, sends a message of healthful and environment-friendly, and blue looks cool and refreshing. Watch out for red, which suggests, sometimes inaccurately, a discount or bargain.

Clip coupons. Consumer Reports estimates that consumers saved $3 billion last year by using manufacturers’ coupons, mostly to be found in newspaper inserts.

So the lesson is: Think nutrition, compare prices and quantities, and – by the way – don’t use up too much gasoline chasing bargains from store to store.