Shoes: Due to their weight, you want to keep these in the corners near the wheels. Because many shoes have metal on them and may therefore require a security check, try to pack them last, in corners close to the top of the suitcase. To prevent scuffs and keep other items clean, store them in plastic bags or shoe bags, one per shoe. If you can, keep sets close together, arranged heel to toe. As for number, you really need only three — something for evening (pumps or sandals), something all-terrain (sneakers), and a good day shoe (sturdy flats). Wear your biggest pair on the plane.

Skirts and Shorts: These should go in the middle layer, on top of heavier pants and sweaters but below blouses, dresses, and nicer clothes. Remember that the fewer times you fold an item, the fewer wrinkles you’ll get. If the skirt is above the knee, simply fold it in thirds lengthwise (folding in half will give you wrinkles in front — right where you don’t want them). If it’s longer, keep wrinkles to a minimum by then rolling from waist to hem.

Socks: Roll some of these up and stuff them in your shoes. For the remainder, pack them last, slipping them into corners and crevices; items will shift only if there are empty spaces, and the socks will act as stabilizers.

Swimsuit: Position this according to what you’re doing — near the top for a beach trip, or at the bottom if you’re simply hoping to squeeze in a dip in the hotel pool. For extra convenience, store the suit in a plastic resealable bag so you can slip it out quickly and put it back when it’s wet.

Sweaters: Pack these below nicer items. Rolling them will help prevent creases in the items above. You can also fold them and use them to pad breakable souvenirs. If you’re pressed for space, they’re great candidates for compression bags — their shape will bounce right back when you take them out.

Tech Gear: Baggage-handling thieves are on the prowl for gadgets, so keep all your main units — computer, camera, iPod — and their cords in your carry-on. Moreover, you’ll greatly reduce the financial toll of lost luggage by having these valuables on hand. If you’re pressed for space, group some cords near the bottom of your suitcase (but be sure they belong to items that aren’t essential to your trip). Bonus tip: “I never go anywhere without an extra laptop battery for the plane and a Y jack so that I can share my iPod — or museum audio guide,” says Rick Steves, founder of the Rick Steves’ Europe Through the Back Door travel-guide series. You can find these Y-shaped cord splitters at just about any travel or tech store.

Toiletries: “Buy duplicates, and give permanent residence in your toiletry bag to as many things as possible,” says Lisa Zaslow, founder of Gotham Organizers, in New York City. “Since this is such a detail-intensive part of packing, it’s almost impossible not to forget something if you’re starting from scratch.” Store the bag down by the wheels (because it’s heavy) near the top of your suitcase (for easy access). Layer one soft item — like a sweater or a nightgown — above it for some extra padding. Tip: Leaky-bottle disasters can happen when changes in air pressure cause caps to open. To avoid this, make sure the bottles you bring are not full. Then squeeze the bottles in and put the lids on. When the air expands, it won’t be able to force out any of the liquids.

Underwear: “Baggage handlers do wear gloves when they go through your stuff. But they don’t change them all day,” says Anne McAlpin, author of Pack It Up: The Essential Guide to Organized Travel (Flying Cloud, $20, www.amazon.com). “If you’re squeamish, store your underwear in plastic resealable bags, two to a bag. That keeps things narrow enough so security can see what’s inside, but they won’t have to open the bags.” Nestle your underwear into corners, or if you do keep them in bags (you can also store them all in one), try putting them at the bottom of the suitcase. They’ll help even out the three dents made by the pulley. The plastic bags will make the garments easy to slip in and out.

Workout Gear: Leave this near the bottom. If you opt for a cardboard divider between your good clothes and dirty things, underwear, and gadgets, group these with the latter.