Coupon clippers, sharpen your scissors and your judgment.

Last year, for the first time in 17 years, coupon use rose with consumers redeeming 27% more coupons in 2009 than in 2008, according to a study by Inmar, a redemption-services consulting firm. That adds up to an estimated $3.5 billion in savings.

Most of the increase of course can be attributed to the rough economic conditions of late 2008 and 2009. Coupons are an easy way for people to stretch their budgets, says Matthew Tilley, the marketing director of Inmar.

But beware: Coupons can also be budget-busters if you let them dictate your shopping list instead of using them to save solely on items you would have purchased anyway. Before your next trip to the store, here are three trends to take advantage of -- and two pitfalls to watch out for.

SAVE: Pair sales and coupons

Manufacturers made coupons more enticing last year increasing the number doled out and raising face values from an average of $1.29 in 2008 to $1.41 in 2009, says Suzie Brown, the chief marketing officer for Valassis, which owns coupon site RedPlum.com. They re trying to stem the tide of consumers going for cheaper store-label products in lieu of brand names, she says. Take advantage by using coupons when the item is on sale in the weekly supermarket circular. You can get the brands you enjoy for less than the price of the store version.

BEWARE: Shorter expiration dates

Expiration rates were 10% shorter during 2009 with most coupons lasting just two to three months, reports Inmar. Keep your clipped coupons in an organizer to make sure you remember them at checkout. Or use a site like Shortcuts.com, which virtually loads coupons onto your loyalty card at chains including Kroger and Safeway. Simply swipe the card at checkout, and eligible coupons are automatically redeemed.

SAVE: Hunt online

Not sure where to start? We ve collected consumer advocates favorite coupon sites and grocery savings sites Before you print, ask your supermarket if it accepts home-printed coupons. Most do, but there are still a few holdouts that won t.

BEWARE: Counterfeit coupons

Stolen and fake coupons are frustrating for manufacturers and coupon-clippers alike, says Bud Miller, a spokesman for the coupon Information Corporation, an industry group that fights fraud. Best-case scenario: A free coupon will be turned down at checkout. Worse, you may have handed over cash or financial information to get the fake. Only download coupons from manufacturer s web sites and big-name coupon sites like Coupons.com and RedPlum.com.

SAVE: Load up your phone

"There's been a lot of buzz about mobile coupons," says Brown. The technology is still in the early stages, she says; the resolution on many phones isn't good enough to accurately display barcodes, and many stores don't have good-enough scanning equipment to read them. Still, shoppers with smartphones can take advantage of apps that offer codes and scannable coupons that can be shown to salesclerks, restaurant servers and other store staff in exchange for discounts.