My first big trip without family was to London with a friend of mine. I had heard to tie some kind of ribbon to my suitcase and told her to do the same. She thought it was a stupid idea. Who would have the same type luggage as she did!?!
Well someone did and her bags wound up in Manchester. When the airline located it, it lost her bag again while transporting it to London. Luckily, she was a size smaller than I was, so she shared my clothes all week.
That trip taught me to always, always, mix the packing between bags. It would have been worse if my bag was lost since she was a size smaller. It was a budget trip and I would have had to buy several new things instead of just picking out some things that I wanted.