After traveling around the world and basically living out of a suitcase for four years, I've learned a thing or two about packing light. Most of these tips came from trial and error to ease an aching back, but also for a basic desire to simplify the travel process. Airports don't need to be a stressful experience if you take the time to plan and pack accordingly.
Pack Less
It may sound simple, but packing less really is the key. It doesn’t matter if you are traveling for a couple weeks or a year, bring only what you would need for about five days...or less. Lay out everything you think you are going to pack, then put back 50% of it. There is nothing wrong with re-wearing things a few times (besides undies, which you can hand wash!) if you aren’t getting dirty and sweaty each day. You only really need a few pairs of pants, a couple shirts and an easy dress, as you can do laundry all over the world. If you don't want to waste time at a laundromat, most hotels have laundry services (if you don't mind spending a few extra bucks), or even in the sink with Tide-to-Go packets. Airbnbs are also a great option as you can look for a place with a washer and dryer.
KISS (Keep It Simple, Stupid)
If you want to travel light, you have to dress smartly. That means no bold patterns or wacky Bermuda shorts. Think solid colors you can wear during the day and then again at night. You can dress up a plain black tee by throwing on a scarf and some jewelry. Guys can get away with a clean tee and jeans or pants. Only bring clothes you love and wear all the time. Don’t waste space on that new, impulse-buy top you that you may or may not feel confident in.
Think Small
Only pack essential toiletries and of those, bring small containers. Since you are not checking any luggage, all liquids must be less than three ounces to pass security. Invest in trial size bottles ($1-3 at your local convenience store). If you run out of something, there are shops all over the world. The same goes for electronics. Try to bring one charger for everything.
Nest
Pack things inside of other things. Don’t waste any space if you can help it. Stuff socks or chargers inside your shoes. Packing cubes are a smart investment to keep your clothes contained. If you have to pack and unpack a few times during your trip, you won't have to waste a lot of time staying organized.
Wear your Bulkiest Items
If you must bring a jacket or sweater, wear it on the plane. The same goes for shoes. Wear taller boots on travel days or your gym shoes, as those things take up a good chunk of real estate in your bag. Make sure to always dress in layers. Instead of bringing heavy sweatshirts and thick fleeces, you can wear a few and shove them in the overhead bin if you get warm. This will allow you to make several outfits out of just a few pieces.