Lost luggage...what a blah!
I try to avoid this by packing light and avoiding check-in luggage altogether. But if I really need to, I make sure my bag is properly labeled inside:
Both of these tags were made using plastic ID sleeves and if you want to make your own, check out the tutorial here.
Most suitcases come with free tags and there are many beautiful luggage tags that you can buy now, there seems to be no excuse not to have one! Now here's a little thing I do when I check-in my bags: I always attach those free airline bag tags even if my luggage is already properly ID'd. I guess it appeases my mind that my luggage has a tiny sign saying which airline it will board. I'm hoping that when the bag handler accidentally puts my bag on a Delta plane and sees the small "American Airlines" tag on my bag, he'll escort it to the proper aircraft. My bag and I are a team. We want to be safely reunited in our destination.
But sometimes by the time you get hold of these tags, it's also the time to check-in! And I do want to fill in the information on the airline tags (in case my bag tag gets lost...I know, it's an endless cycle!) in legible letters -- there seems to be no point if the kind soul who finds your bag can't read your handwriting.
So days before my trip, I make these print-outs on adhesive labels that I can just stick-on the airline tag. I make enough especially if there are different legs of the trip that will require checking-in my bags.