The goal is not to be clever; it is to stop carrying your apartment with you. Ten days in one bag works if every item earns its place twice: once for how often you will wear it, and once for how easily it mixes with everything else. Start by laying out everything you think you need, then put half of it back.
The core is a uniform: two pairs of trousers or shorts, three shirts that work in any combination, one sweater or light jacket, underwear and socks for five days with a sink-wash halfway through, and one pair of shoes besides the ones you fly in. Roll everything tightly; a packing cube or two keeps the bag organized and easy to repack.
The test for a bag is simple: can you carry it for twenty minutes without shifting shoulders? If not, the bag is the problem, not the trip. When in doubt, leave the item at home — the thing you truly need costs five minutes and a few coins in any city.