SENDING THEM PACKING : An expert reveals how vacationers can take the wrinkles out of their summer trips.

Ever wonder why it’s so easy to spot summer tourists in Orange County?

For the same reason they can spot you when you’re away from home.

“Their clothes look like they were packed in a Dixie cup,” says Marilyn Maxwell. Wrinkles, wrinkles, wrinkles.

Wrinkles on their faces, too, from the pain of lugging a complete set of bulging bags and suitcases. (Why do you think they call it luggage?)

And what’s inside to justify all the sweat and inconvenience? Extra clothes they’ll never wear, extra cosmetics they’ll never use, and always the giant, economy size of everything. All packed “just in case.”

“The ‘just-in-case’ can fill two suitcases,” Maxwell says. “There’s a tendency to do it even on weekend trips.”

Who is this Maxwell who sounds so superior? She’s the woman who went to Guadalajara for five days with only a carry-on flight bag and a purse, “and I dressed differently for dinner every night.”

That alone qualifies her for her job: Coastline Community College’s professor of packing. More precisely, she has been instructor of the college’s workshop on packing during the last 12 years, and hundreds of people have paid to learn her secrets.

But there are no genuine secrets, Maxwell says. Her rules of packing are so obvious that her students at first refuse to believe them. “They think I have a genie that comes out or something. They can’t believe they didn’t think of that themselves.

“It’s insecurity. Most people are very insecure when traveling, when they’re not on their own turf. So they overpack.”

Maxwell makes it plain that she’s talking about women. Men tend to err in the other direction, she says.

“Men throw their clothes in and say, ‘Let’s go.’ We females, we’re almost all clothes horses, and we try to take it all. One of my students had three large suitcases for a short trip. There was no way she could wear all those clothes if she changed every hour. Another student always took her curling iron, hair dryer and hot rollers. That’s enough right there to fill up a flight bag.

“There is not a husband or boyfriend who does not complain about this. It is one of the biggest pitfalls. He says, ‘Let’s go to Hawaii,’ and she hears, ‘Let’s go shopping.’ ”

But cheer up, for what follows is the Maxwell method for going anywhere for almost any length of time with only one medium-size suitcase and one flight bag.

Secret No. 1: As soon as you know you’ll be going somewhere--whether it’s next Friday or next fall--start your preparations.

Buy nothing. Gather nothing. Pack nothing. Instead, ask yourself some questions that will make you realize what kinds of clothes you really need.

Will you be spending most of your time indoors or outdoors? Are you going to be eating out? If so, will you be eating at La Grande Addition or at Der Wienerschnitzel? Will you be going to ambassadors’ balls or to cookouts?

Will it be hot or cold or wet? Will you be doing a lot of walking? Are you going to be traveling every day or spending days in one place?

And of surprising importance, with whom will you be traveling? How fancy you want to dress has a lot to do with whether your traveling companion is your college roommate, the new man in your life or your husband of 20 years.

Secret No. 2: Armed with an idea of your real needs, chose the one basic color for your wardrobe. According to Maxwell, this is the key to success. Everything you take will either be that color or complement it.

“My basic color is always black, but you can choose beige or brown,” Maxwell says.

“The whole secret of packing is to be able to use one outfit four or five different ways. You have a skirt-and-top outfit, so you make sure that the top goes with a pair of pants and that some other blouse and maybe a halter goes with the skirt.

“Then you take three jewelry-and-scarf sets for each outfit, and you roll the jewelry in the scarf it goes with. Each set can make the same outfit look entirely different.”

Using this principle, you can easily spend two weeks at a convention or in Europe with two suits and three two-piece outfits, Maxwell says.

But be careful of certain kinds of clothing.

Dresses and jumpsuits don’t mix with any other clothing and should be avoided unless you must have them.

Sexy nightgowns become inconvenient when you must leave your room and head down the hall toward the bathroom. Better to sleep in modest nightshirts or long T-shirts than to take along a bulky robe to cover up.

And avoid any garment about which you say, “Now I can wear this!” “A blouse you bought in 1987 and haven’t worn is not suddenly going to be beautiful in London,” Maxwell said.

If you’re going somewhere really cold, take no more that one heavy coat, pack your gloves and muffler in its pockets and resign yourself to carrying it.

But consider first whether you really need it. If you’re only out in the cold between the museum and the hotel, better to take jackets and sweaters you can remove in heated rooms. “Lightweight turtlenecks that go under things are what you want,” Maxwell says.

A London Fog type of raincoat supplemented with an umbrella small enough to pack in a suitcase is the best means of dealing with rain, Maxwell says.

Secret No. 3: Select the one outfit you will wear while actually traveling. The uniqueness of this outfit is that you never have to pack it; it either hangs on you or in the closet of your room. So while it must be comfortable and practical, it can also serve as your dressy outfit.

“A suit is always the best choice, or a dress with a jacket, but make sure the jacket can be worn with other items in your travel wardrobe,” Maxwell says.

Now that you know what you need, you can start selecting your clothes and buying whatever is required. Either hang these clothes separately in your closet or make a list of them for packing day.

Secret No. 4: The Box. Set a cardboard box in some obvious place and put into it the odds and ends you know you’re going to need.

“These items normally are in a half-dozen different places in your home, and there are too many of them to remember when you’re packing,” Maxwell says. “You know you’re going to need extra film. So buy it now and put it in the box.”

Also put in disposable razors (“Never rely on anything electric”), extra panty hose (“They’re hard to find overseas, and they never seem to fit”), medications, extra glasses and all the whatevers you’ll need.

Now, according to Maxwell, all the hard work is over. Actual packing is done at the last minute--never earlier than the day before departure--because it’s easy, “like stacking them in a box.” That literally is how Maxwell packs her clothes.

She favors a light, medium-size, soft-sided case whose side zips open and folds back, revealing a box-like cavity with no compartments or dividers. It must have wheels for drawing it along with a leash. “Wheels are a must. Never buy anything without wheels,” Maxwell says.

Even the flight bag--anything you can carry onto an airliner and tuck under the seat--should stand upright on wheels, she says. “That way, when you’re standing in line, you can just nudge it ahead with you.”

The flight bag is your purse and should not contain any of your heavy items. It should contain, however, one change of clothing and one pair of all-purpose shoes as protection against the day when your suitcase is accidentally routed to Tasmania.

A few more tips from Maxwell:

* Don’t forget your identification. “People end up going with nothing but their passports. Lose it, and it’s very hard to replace without other ID. Always take your driver’s license and a credit card.”

* Take only shoes that have proved themselves to be true friends. And never pack shoes empty. They can hold a lot of extra underwear.

* Always button garments before packing them. “It’s a pain, but it helps prevent wrinkling.”

* Always fold sleeves back at the shoulder seam, because a wrinkle there is less noticeable.

* You can remove most wrinkles by hanging up a garment, lightly spraying it with a fine mist of water and letting it air-dry. Take a small spray bottle for this purpose.

* Buy the smallest amount of such items as toothpaste and deodorant. Use a little of it before packing or it could explode in the unpressurized bay of an airliner. “The smallest tube of toothpaste looks like a gallon after it’s exploded in your suitcase,” Maxwell says.

* Take only the cosmetics you use every day.

* Seal nail polish and remover bottles in a plastic bag. Maxwell says their caps always seem to come loose.

* And if a night light would give you comfort in strange bedrooms, take one with you.

Oh, yes, just what did Maxwell take to Guadalajara?

She wore a beige jumpsuit and high-heel buckskin boots. In her purse she carried cosmetics and a small hair dryer. In her flight bag she packed flat shoes, black high-heels, a black-and-white chiffon pants-and-jacket outfit, a black, sleeveless T-shirt, a sequined halter, a plain black knit pants-and-top outfit, a chiffon jumpsuit in metallic colors, two pairs of cotton pants and tops and lots of scarfs and jewelry.

“But I came back with three suitcases full of stuff I bought down there,” Maxwell says. “Sometimes I don’t take my own advice.”

MARILYN MAXWELL’S SYSTEM FOR PACKING:

1--First pack pants. Place first pair flat across the bottom of the case with the cuffs touching Side B and the tops hanging out over Side A. Smooth out all wrinkles. Place the second pair of pants over the first with the cuffs against Side A. Continue alternating sides until all pants are in.

2--Pack skirts. Place first skirt on top of pants with the hem touching Side C and the waist hanging out over suitcase front. Smooth out all wrinkles. Place other skirts in same position, hems touching Side C.

3--Pack jackets. Button all jackets. Place first jacket on top of skirts with hem touching suitcase front and collar hanging out over Side C. Fold sleeves at shoulder seam. Smooth out all wrinkles. Place other jackets in same position, hems touching suitcase front.

4--Pack blouses and shirts as you packed jackets, but with hems touching Side C and collars hanging out over suitcase front.

5--Pack jump suits. Fold them in half lengthwise, smooth out all wrinkles and place them with top hanging out over Side A and cuffs hanging out over Side B.

6--Pack soft, non-wrinkling garments such as underwear, sweaters, T-shirts and pajamas. Do not fold them; roll them individually and place them inside the suitcase snugly against the sides and ends.

7--Place shoes (individually inside plastic bags, if you wish) in the well formed by the perimeter of rolled garments. (Extra underwear, scarves, jewelry and other items can be packed inside shoes.) Place any other heavy items in this well, too.

8--Cut a piece of slick poster board to fit inside the suitcase and over the rolled garments, shoes and other items. This eliminates their lumpy surface.

9--With the poster board in place, carefully fold in each item hanging out over the edges of the suitcase. Smooth out any wrinkles.

10--If you chose your clothing wisely, the top of the suitcase will zip shut without strain.

Unpack exactly as you packed if you’re planning on being in one place for more than two days.

If you’re touring and just need one outfit, don’t unpack. Just pull out what you need for that day and re-pack the next morning on top of the poster board.