It took me many trips to understand that packing cubes are helpful only if you use them right. Dedicate half of your suitcase to the one-off outfits — the dresses, skirts, and flare jeans you may only wear once. Use the Marie Kondo method of folding to keep everything neat and compressed. (It's really easy to squeeze additional items in that way.) The other half of your suitcase should be for packing cubes. Use them for intimates (bras, socks, underwear) and the basics you'll be reaching for…