I won't say I'm a packing expert, but I have done it a few times, and there are certain methods I have found to work better than others.
1. The key is to not overpack, because not only does a large amount of luggage often cost more to put on a plane (if you're travelling by air) but also becomes quite a burden to keep a handle on. It also doesn't leave much allowance for anything you might want to bring back with you, whether you've gone shopping or have a few souvenirs. Pack light & leave a small allowance for the return trip.
2. Pick out your outfits ahead of time. If at all possible, get a list of the activities you'll be doing each day, and plan your clothing accordingly. This saves so much time on the days you're actually wearing the clothing, keeping you from having to rumple through your bag and piece together an outfit and also keeps you from overpacking "essentials" that you may or may not actually wear. Be sure to also check the weather an make sure you're choosing clothing appropriate for the climate.
3. Shoes on the bottom, roll your clothes. These are the two most important things about packing that my dad has taught me, and it's the difference between a suitcase that looks nice before you close it (but not when you reopen it at your destination) and one that stays put and organised. Plus, rolling your clothes neatly saves a lot of space.
4. Keep it lightweight; dresses, slender sandals, shorts, t-shirts. One pair of pants is usually all you'll need in that department in the summertime. Use a few standout accessories to mix it up, or to elevate the elegance, but don't go overboard on the jewelry; I find that I almost always overpack jewelry, and in the end I probably wear the same watch and rings the whole trip, maybe swapping in a necklace and earrings here and there. Unless you're going to a fancier event, keep it simple, delineated.
5. Pick a good, sturdy bag...because you'll probably be using it the whole trip. If I'm travelling by plane, I like to have something big and structured enough to support a good few books, and also have room for my essentials (a few small makeup essentials, pens, my phone, earbuds, wallet, travel journal). But I don't carry all of this around with me during the rest of the trip, so I make sure I have room in my suitcase for a small crossbody (flatpack or slide it down the side of the suitcase). This way I don't have to carry everything in my pockets, nor am I lugging a large handbag around sightseeing. A crossbody is handsfree, lightweight and easy to keep track of.
What are your best packing methods?