After a million-plus miles in the air, 70-odd countries and countless visits to a cold hometown for the holidays, the packing wisdom I've learned comes down to this: It's all about shoes.

It's shoes that eat up space in your rollaboard, right? So the key to packing in a carry-on is to limit shoes to the pair on your feet (the heavy pair, say boots), with a second pair (dress shoes) in your rollaboard.

Of course, even if you're a fashion-challenged rough-and-tumble sort, you know that tan shoes may not work with your gray slacks. That realization leads to the cardinal rule of packing efficiently: color. You can only take clothes in colors that go with the shoes.

But can you really make it for the holidays in the Cold Zone and get all your gear into a carry-on bag? If you're going to a black-tie event and backpacking on the same trip, maybe not. But if you're heading out for family time around the house, visits to local attractions and one or two dressy meals, you'll be fine - and even have room for that extra gift you forgot to drop in the mail.

And you care about getting it all in your rollaboard because . . . it's the holidays. Between weather uncertainties, crowds and general mayhem, chances go up that you'll have to make some last-minute change or get delayed. Having your luggage with you can ease the pain.

Here's how you can fit in clothes enough for a week. These tips work any time of the year - and for men, too.

* Plan ahead, says Susan Foster, author of Smart Packing for Today's Traveler (Smart Travel, 2000). Knowing what you're going to do will help you decide what clothes to take.

Many experts recommend making checklists and putting out all clothes a week in advance, then paring down to half. Impossible in my time-pressed household - but I do try to put out clothes at least a day in advance so I can think through what I'm really likely to need and make any button repairs before I leave home.

* Stick with one basic color. Mine is black - black shoes, trousers, a little black dress, with the occasional item in gray and even a sweater in blue. To stave off boredom and avoid looking dour, I bring along costume jewelry, a light evening purse, pashminas and scarves in bright colors - items that are lightweight and pack easily.

* Wear layers. Lightweight tights, camisoles and long-sleeve T-shirts fit easily under lightweight sweaters and a jacket.

* Stick with knits. They pack flatter.

* Leave bulky items at home. This means some of my fave sweaters don't go north. But I long ago decided showing them off to my sister isn't worth the hassle of checking my bags.

* Pack tightly. After experimenting with all kinds of packing devices, I've narrowed to two types: envelopes and packing cubes.

If your rollaboard bag doesn't have a separate compartment for hanging clothes, use a packing envelope (mine comes from Eagle Creek) that keeps trousers, blouses and even knit dresses flat.

Packing cubes - both Eagle Creek and Magellan sell them - with a mesh top keep items compacted but allow them to breathe. I use a small size for underwear and socks, larger ones for T-shirts and sweaters.

I'm not keen on the plastic bags used to "vacuum" pack clothes; the bags don't hold their seal and the clothes come out wrinkled. But if you're traveling with kids, you may want to use your regular super-sized resealable plastic bags for organizing their clothes (tops in one, bottoms in another) so you can easily find clothes. Take an extra, empty bag for items that end up wet or messy.