Data on an SD or CF memory card is pretty safe. If you won’t be traveling long you could just take enough cards to handle the number of photos you’ll shoot and download them when you come back. Memory cards are cheap and don’t crash often, but they are pretty easy to lose. I’m not a fan of huge capacity cards for two reasons. If one does get corrupted you run the risk of losing all your photos. The more important reason is that if you’re shooting on a card that holds thousands of photos, you’re likely to make it through a whole week or trip before you fill one up. That means that your camera, which is the likeliest thing to get stolen that you’re carrying with you, has all your precious photo memories in it. If your camera is lost or stolen the pictures go with it. I prefer to have several cards of smaller capacity and leave the extra cards in the hotel room in plain sight. If they’re tucked away in your camera bag they are likely to be stolen along with everything else. A little paranoia can pay off when protecting digital files.
Get a good memory card holder or wallet. My favorite by far is the Pixel Pocket Rocket by Think Tank. It comes in two sizes, one for CF and one for SD cards. It folds over, holds your cards securely, holds business cards and has a fob with a clip. This is a great idea and one that gives me a lot of peace of mind. I clip that thing to a ring on my camera bag or loop in my jacket and don’t have to worry about accidentally dropping all my memory cards in a river or through a subway grate.
If you want to backup your data while you’re traveling, there’s a temptation to just download them into your laptop, then reformat the card and shoot some more. Don’t do this! You have moved your data from a very secure, low theft device like a memory card to the spinning hard drive or SSD memory in your shiny, more-likely-to-be-stolen laptop. If you want to use your laptop, either keep the data on the cards as well or take an external hard drive with you to backup the files on. My favorite storage device is the Samsung T5. It’s available in .5, 1 and 2TB. They are much more expensive than external hard drives but they are tiny, lightweight, fast and completely not prone to physical crashes the way hard drives are. The laptop and hard drive shouldn’t be in the same bag at the same time to avoid a total loss in case of theft. Data backup maxim: Data should be stored in at least two places at all times, and one of those should be in another location.