Mom was right about saving money on groceries by shopping on a full stomach. And though you may have felt like the Michelin Man, she had a point about layering, layering, layering until coats went on sale in February.

Mom, value stock investors, and your everyday millionaires -- the rich and not-so-famous ones -- know the secret to saving a fortune: Never pay retail.

But does Mother know the best time to pick up a cheap set of golf clubs (September) or house-painting supplies (that'd be April)? Pro shoppers like moi and the folks at The Washington Post do: The trick to getting a bargain on just about anything is to buy it when you don't need it.

Mark your calendar (the one you bought at 75% off last January) for the best buys over the next 12 months:

January: Besides calendars, datebooks, and all things Christmas, January is a good time to score cheap TVs and bedding -- high-thread-count sheets for the guest bedroom, please.

February: Use that old coffee table for kindling and replace it (and that threadbare couch, while you're at it) with new furniture. Outerwear is also on sale this month. Though the selection may not be the best, the prices on winter coats will warm your heart.

March: Your heating bill still says it's winter. But Home Depot has summer on the sale rack -- and air conditioners are priced to move. If visions of skiing are still in your head after that horrible tumble you took on the slopes last month, you can pick up discounted winter sporting equipment and, strangely enough, frozen foods. So stock up on frozen peas to cut the inflammation on your bum ski knee.

April: Feeling like a couch potato after the long winter? Those fliers for bargain home-improvement items -- such as flooring, gardening supplies, and house paint -- covering the dining room table are your significant other's way of saying, "Get off your duff." (Though if your spouse likes to overspend, harmoniously reel in the household credit card.)

May: If you're going to get stuck in Memorial Day traffic, it might as well be on your way to pick up sale housewares, some appliances, bedding, and bargain spring clothing.

June: The brides already have their gowns -- this is the month to get their rejects on sale. Also good buys are sporting goods and menswear -- if you can tell the difference between the two.

July: Put on your game face, gadget freaks -- it's your turn to hit the mall. Electronics and major appliances are hot buys in July.

August: Bikini season is almost over, and by now you're just 10 pounds shy from fitting into that suit! Go ahead and scarf down the leftovers -- garden furniture, grills, beachwear, sunglasses, and, of course, a new bikini in your actual size. Remember, the tag is on the inside of the garment. Fit and style trump size every time.

September: Just as you start turning down the A/C, it's time to buy a new one. September sales are also a great excuse to get new golf clubs at a discount.

October: If the kids can make do with scrap paper and pencil nubs until you can get them new school supplies on sale this month, tell them you'll throw in a new bike. Only you need to know that the wheels were marked down to move, too.

November: Turn off the space heater and snuggle under those sale blankets and quilts. You may even be able to pick up a real estate bargain -- like a second home in warmer climes.

December: Shoes, glorious shoes! Stock up, ladies -- and don't miss the sale sweaters and wool separates. Other end-of-year cheapies include baby furniture and cell phones that didn't find a spot under anyone's Christmas tree.

Are you a discount diva? Want to go pro? Read on:

When's the best time to buy stocks on sale? All year long, with a little guidance from Philip Durell, who heads up our Motley Fool Inside Value newsletter. Philip's specialty is finding stocks marked down well below their true value. Go shopping with him with a 30-day trial subscription -- free!

Dayana Yochim owns several of the accessories mentioned in this article. The Motley Fool's disclosure policy is a bargain at twice the price.