Pack one full outfit for every two days and have children wear each piece of clothing more than once. Bring one pair of underwear and socks a day, plus a few extras. Bring dark-colored clothing, as children are bound to get dirty and dark clothing won't show the mess as much. If you're going someplace warm, pack two bathing suits. Bring at least one sweatshirt for evenings and cool weather. Pack one pair of pajamas for every four days. At least one pair should have long sleeves and pants in case you're in an air-conditioned room. Unless you're planning on any nice dinners out, one pair of sneakers and one pair of sandals should be adequate for trips to warm locales. For cold weather, bring warm boots and a parka. Add a hooded windbreaker in case of rain.
Entertainment items are crucial, particularly with long car or plane trips. Pack a tote bag filled with fun items to keep children occupied. Load an iPod or other mp3 players with children's dance music, lullabies and audio books. Create an art kit with coloring books, stickers, stencils and crayons in a plastic bag. Avoid markers or paints. Tuck a few books and card games in as well.
Being away from home can be difficult for any child. Ease the transition with familiar items from home. Sleeping in an unfamiliar place is particularly difficult, so pack the child's pillow and favorite blanket if possible. If you're traveling by plane, bring a smaller throw pillow from the child's bed. If the child is traveling without his family, tuck some photos of the house and family into his bag. By all means, don't forget the child's special stuffed animal or blankie. If the child sleeps with it, you can't pack it the night before. Tape a note on the inside of the front door to check that you have it before leaving.
Once the basics are packed, think through the other objects that your child uses on a daily basis. For babies, pack more diapers and baby food that you expect to need. Pack general medications like fever reducers, cold medicine and bandages. If headed to the beach, pack a few buckets, shovels, inflatable rafts and beach balls. Snacks are crucial, too. Avoid any foods that are smelly. Pack sandwiches or dry cereal in hard plastic containers to keep them from getting crushed. If you're traveling by plane, bring hard candy or gum. Pass these out to older children to chew during take-off and landing to prevent painful ear popping.