I've never (*knock on wood*) lost any travel photos from a trip, but I've definitely heard horror stories from fellow photographers and internet goers. I think losing your photos is among one of the biggest fears while traveling because they're the only tangible source of your memories. From my own experience and the lessons I've learned from others, here's some key tips on how to keep your photos protected while traveling:
1.) Format your cards before the trip
First and foremost, format your cards before you set out on your trip. Traveling without a computer is probably the best decision you can make, but that means you'll need to capitalize on the amount of space you've got on your cards. You definitely don't want to be four-days in to your trip only to find out you're completely out of memory on your cards. So format your cards before you leave to maximize the space on your cards.
Even if you do plan on bringing your computer, you should still format your cards ahead of time so that your photos will be more organized when you go to download them at the end of your trip.
2.) Keep your cards in a designated spot
This might be obvious to some of you, but to all of my unorganized friends out there - you have got to keep your cards in a designated spot during your trip. Don't have them floating around in your bag or a pocket. Invest in a case or use a small coin purse if you must. Whichever you choose, make sure your cards are always in their designated place or in your camera. Nowhere else. There's a lot going on when you're traveling and the best way to keep your mind at ease when it comes to your photos is to keep your cards in order.
3.) Keep your cards on you
During your trip, you might have to take a bus, train, or a plane. In the event that your bag will not be on your lap or below the seat in front of you, make sure to keep your cards on you. Do not leave your cards in your suitcase and put them in the overhead bin. Never ever put your cards out of sight when you're in a public place. If someone steals your bag, then at least they haven't stolen your memories.
If I'm put in a position where I need to put a bag out of sight (an overhead bin on an airplane, train, or bus is out of sight! Theft happens in overhead bins.) I usually take the card that's currently in my camera and hide it in my wallet. Then I take my card case (with the rest of my cards) and put it in whatever bag I have with me in my seat, or the bag I keep my wallet in.
4.) Create a System
Before you travel, train yourself to follow a fool-proof system with your cards that works for you. For example, my system is that after I've filled up an entire card on a trip, I'll put it back in my card case upside-down. This informs me that I've already shot on that card, that way I'm not enticed to pick the card back up until I get home and download it.
If you're shooting with SD cards, they usually come with a built-in "lock" function that you can take advantage of though I still recommend coming up with a back-up system just in case.
5.) Download your photos immediately
This one should be obvious, but I know even my own fiance struggles with this! Download your photos immediately! Do not wait. The faster you copy them over, the better. There's less room for error, less chance of you forgetting, less chance of the cards getting lost, etc. etc. Just do yourself a favor and download them.