Your office-pantry machine doesn't make perfect coffee. Nor does the man who works the newsstand. But you can make the best-tasting cup by following these six brewing rules.

1. Buy 100 Percent Arabica Beans

Look for labels that say "100% arabica." These beans are richer and more flavorful than easier-to-grow — and cheaper — robusta beans. If you don't see "made with arabica beans" on the label, you can assume you're getting robusta beans. Coffee made from arabica beans has half the caffeine of that made from robusta beans, so medical residents and airline pilots might want to stick with robusta.

2. Forget Beans in Bins

Plastic bins might look appealing, but there's a good chance the beans they hold are rancid. Two of the biggest flavor-busters for coffee beans are light and air, and plastic containers offer little protection against either. Plus, the beans' oils adhere to the plastic and turn stale. "It takes lots of hot water and scrubbing to remove the gunk — a low-priority chore in most supermarkets," says Corby Kummer, author of the updated The Joy of Coffee, $16, www.amazon.com. "When new beans are added to the bin, the old, rancid oils can `infect' the new beans with their off flavor."

3. Look for Vented Packages

Supermarket coffee is fresher than it used to be, thanks to new venting technology. Today coffee in bags or cans with valve vents, which let carbon dioxide out but don't allow oxygen in, generally makes a better cup than beans in nonvented packaging. Look for a small round disk on the front of a bag or under the plastic lid of a can.

4. Match the Maker to the Grind

Keep in mind that the finer the grind, the shorter the brewing time. French presses call for coffee that's ground to kosher-salt coarseness. Automatic-drip coffeemakers work best with a medium grind, about the size of cornmeal. Espresso makers need a grind the size of granulated sugar. The coffee grinder at the store may give you a more even grind than a propeller mill at home, but unless there's a dedicated mill for flavored coffee, the beans you grind there may take on the flavor of the previous customer's Irish Cream. Drop in a handful of beans and grind them to "clean" the mill, then add the rest of your beans.

5. Store Well

You can extend the life span of whole beans by pouring them into an opaque canister fitted with a rubber-ring—sealed lid. (Plastic lids on cans and metal twisties on roll-down paper bags do not protect coffee from oxidation.) Keep no more than a two-week supply at room temperature in a dark part of your pantry. Storing coffee in the freezer will protect it from oxidation and moisture, but Kummer warns that the beans' flavor could be compromised.

6. Measure Carefully

The recipe is simple: 2 tablespoons of ground coffee for every 6 ounces of water.