May is a celebration-filled month, from Mother's Day to Memorial Day, not to mention the start of graduation season. As a gift-giving month, the deals in May are plentiful, but shop with caution — what looks like a steal may be a swindle in disguise. Here analysts from CreditDonkey.com, a credit card comparison website, and a deal site, Offers.com, break down the data on some of the best and worst deals this month.

What to buy

Caribbean vacations: Travel during shoulder season and you will benefit from smaller crowds, warm weather, avoidance of hurricane season and up to 65 percent off hotel stays, says Chris McGillicuddy, spokesman for Offers.com.

Mattresses: Anyone in the market for a new mattress knows May is the time to strike. Memorial Day mattress sales are generally the best time of the year to get discounts in the range of 50 percent off or more. Also look to score discounts on bedroom furniture through special financing deals and dollar discounts.

Refrigerators/kitchen appliances: Retailers begin rolling out new refrigerator models over the summer, says Lauren Ward, research analyst at CreditDonkey. In May, look for markdowns on last year's models to save. You will also find financing deals (such as zero percent interest), but be sure to read the fine print. Retailers will also offer deals on other kitchen appliances such as a stove or dishwasher. Expect to see savings of up to 30 percent.

Spring apparel: Jump on spring clothing this month and find discounts of 40-80 percent off, according to McGillicuddy. Prices will get lower closer to summer, but the selection will also dwindle. If you want more than remains, check inventories this month to see if your size is in stock, then decide if you want to take a chance and wait. If you are an outlet shopper, you'll find great apparel deals and discounts for Memorial Day. Sign up for email alerts from your favorite brands to get coupons for extra discounts of 25-40 percent.

Cookware/kitchen appliances: Cookware is a common gift item for moms and grads, and this month expect retailers to discount cookware up to 78 percent, McGillicuddy says. In addition, if you're planning a party, look for deals on party supplies toward the end of the month, as retailers reduce prices to avoid having excess inventory on those items when party season is over.

What not to buy

Jewelry: This is a tough category since early in May, you are likely to see small discounts on jewelry to draw in Mother's Day shoppers. Don't be swayed until later in the month, when you can save on Mother's Day clearance sales, particularly if Mother's Day sales are slower than expected.

Outdoor equipment: Lawn mowers, patio furniture, grills, etc., are purchases best left for late summer. Prices are at a peak now as shoppers prepare to head outdoors. Wait to buy grills until July, Ward says. For lawn mowers and patio furniture, fall will bring the best buys. If you must upgrade, consider shopping secondhand or just freshen up the cushions on furniture.

Swim and summer apparel: It's natural to want to replace last summer's duds with fresh items, but with swim and summer apparel just rolling out on store racks, you'll pay a premium, McGillicuddy says. Try shopping in August or September to get the best deals and you'll be ready for next year.