NEW YORK — It's time to think of the inside of your carry-on suitcase as real estate: Make the most of what you've got, keep it functional and make neatness count.

The carry-on bag could be the solution to some of the summer travel season's likely woes — including checked baggage fees on American Airlines and possibly other carriers — but it also has the potential to cause headaches. You don't want to find a rumpled mess when you arrive at your destination or spend your vacation shivering or sweating because you weren't ready for the weather.

It is possible to pack fashionable clothes in an efficient way. Some tips from the pros:

CHOOSING A GOOD BAG: Wendy Perrin, consumer news editor for Condé Nast Traveler, uses a standard rectangular-shaped bag with wheels for business trips because clothes are less likely to become wrinkled. For recreational travel, however, she prefers soft-sided duffel bags.

"One way to pack play clothes to fit into space more economically is to roll them and stuff them into a bag like cigarettes into a cigarette box," she says.

Perrin doesn't buy into bags with a lot of compartments, mostly because all those zippers, flaps and folds add unnecessary weight. Instead, she separates undergarments and socks into one zip-top plastic bag, tech gear such as cords and batteries into another, and toiletries all in yet another. (Any liquid needs to be stored in a see-through bag.)

"You want to start with the empty cavern and make your own compartments with smaller packs," agrees travel-gear store Flight 001 founder Brad John.

John says that you might be asked to open carry-on bags during a security check. It will go much more smoothly if items are organized than if everything comes spilling out.

But Deborah Lloyd, co-president and design director for Kate Spade, says her bag has a roomy outside pocket for easy access to her laptop and magazines.

Be mindful of your airline's size limit for carry-on bags. American's, for example, is 45 linear inches.

WHAT TO PACK: Perrin chooses a neutral color palette — maybe blue and tan, maybe black and white — and then sticks with it for the trip. By limiting the number of colors and patterns, everything matches and there's no need for that extra sweater to go with the lime green skirt. To keep her wardrobe from being boring, she'll pack colorful scarves, which, she notes, take up very little room in a bag.

Susan Foster, author of "Smart Packing for Today's Traveler," tucks her accessories into her shoes, filling up what would just be wasted space.

And bring things you love: If you're going to wear the same sweater several days in a row, make sure it's one that makes you feel good, says Foster, who also runs www.smartpacking.com.

"If I have my favorite choices, I don't mind wearing them day after day. You can always wear them in different combinations," she says.

Jersey fabrics, as well as washable silks and athletic fabrics, usually pack flat and travel well, according to Foster. She recently became sold on The Limited's new travel suit, made in a polyester-wool-and-Lycra blend, because it has a slimmer, more modern cut than most travelspecific clothes.

Perrin believes in the layered look, with enough T-shirts, camisoles or shells for each day, but only one sweater and light, water-resistant jacket to go on top.

Toiletries take up a lot of room and liquid products are subject to the 3-ounce security rule, so Foster has moved toward dry products, such as a stick deodorant and mineral cover-up makeup, when she can. She'll also pack shampoo with a built-in conditioner and moisturizer with SPF.

WHAT TO LEAVE HOME: "A different outfit for every day is the worst strategy because you might need different shoes, a different handbag and different accessories for each one," Foster says.

Instead, she suggests, switch out only the pieces that other people notice. "Change the tops, scarves, etc., but who'll notice which black pants I'm wearing today?"

Jeans might be the basis for many vacationers' wardrobes, but not Foster. They're too bulky, can't effectively be washed in the sink and take too long to dry, she says.

Too many shoes are the downfall of many packers. Women shouldn't travel with more than three pairs, says Foster, and men, simply because their shoes have a larger profile in the suitcase, shouldn't have more than two.

For most trips, she can live with a comfortable pair of walking shoes and a pair of dressier shoes for dinner.