For a 10-day trip, the most efficient approach is not to pack 10 unique outfits, but rather a "capsule wardrobe" of about 6 to 8 versatile sets. A widely recommended formula is the "5-4-3-2-1" rule: 5 tops, 4 bottoms, 3 pairs of shoes, 2 dresses or outerwear pieces, and 1 set of accessories. This allows for over 20 different combinations through mixing and matching. If you are traveling to a warm climate, you might lean toward more tops (about 7 or 8) since they take up less space and are more prone to sweating. Conversely, for a city break, 3 pairs of versatile pants (jeans, slacks, and a skirt/shorts) paired with 6 shirts usually suffices. The key is to pack items in a cohesive color palette so that every top works with every bottom. Don't forget to pack 10 to 12 sets of underwear and socks, as these should generally not be reworn. If you have access to laundry, you can easily cut the main clothing count in half, allowing you to travel comfortably with just a carry-on for the entire duration of the trip.