When you getting aboard or just leisure shopping, it's better to take this simple neck wallet that can have your valuables / handy items around your neck and tucked into shirt or jacket instead of having a luggage or your backpack.
An ideal EDC organizer bag, cell phone, earphone, keychain, keys, small gadget, pens, ID cards, credit cards, license, cash, passoort, etc. Everything else you need readily accessible.