Write down everything you need for your vacation destination, such as swimwear, evening wear, play clothes, sleepwear and shoes. Include a sweater or coat. After you make your list, rethink how you can make substitutes go a long way. How about a warm shawl that substitutes for a sweater and that you can wrap up in on the airplane? Can you use your swimsuit cover-up for a shirt over shorts or long pants? T-shirts can carry a color scheme over several outfits. One scarf can be a belt, a neck wrap or a head swathe, not to mention a halter top. Every item needs to do double duty, which means a skirt and top is better than a dress if it can be worn with other pieces. An additional reward is that you won't be paying the airlines cash for extra baggage.
Try out pink, green and yellow, or red, white and blue, or even lavender, beige and cream. Avoid black because the color shows dirt and attracts heat. Build your wardrobe around the three colors you can mix and match to make endless varieties of looks with a minimum of actual garments.
One pair of socks and tennis shoes is all you need for walking all over town. When you return to your room, air out the sneakers and rinse out the socks so they are ready to substitute for bedroom slippers. Sandals are evening ready if you clip on a pair of glitzy earrings to zip up the style quotient.
Learn the art of the 2-second shirt fold. See Resources. Once the shirt is smooth and wrinkle free, roll it onto an empty paper towel tube. Watch the video on how to fold pants and shorts, and roll them up as well. Stuff scarves and socks into the tubes. Tuck in a minimal amount of jewelry. Place shoes heel to toe in plastic bags. Secure them with rubber bands. You will be surprised how many times you will reuse those bags and the rubber bands. Place shoes in suitcase pockets and add your hair spray and toiletries, all bagged in case something leaks. Stack your tube-rolled outfits like cordwood along the bottom of the suitcase. If you must have a dress, place it in a plastic bag and make it the last item you insert before zipping the bag closed.
Wear your most comfortable pair of jeans that are really bulky, plus a sweatshirt over a T-shirt, onto the plane. Put on your sun hat and carry your makeup in your purse in case you are separated from your luggage. Wear your bulkiest shoes and tie an extra scarf to your handbag. You are actually wearing two days worth of outfits if you need them. Sneak in a pair of underpants as well, because you certainly can't wear your undies for days on end until the luggage catches up with you. The more you think about how to combine and repurpose your clothing, the easier it is to show up with a small bag full of a week's worth of looks with barely a repeat. Don't be surprised if there is room left over for souvenirs on the return trip.