When traveling, your standard backup procedure (you have one, right?) is probably not available to you.
In addition, the pictures you are taking while traveling are likely unable to be re-shot without great effort and expense, making a backup of them even more important.
As always, the premise of a photo backup strategy is: the more (reliable) copies of the original photos you have and the more locations these copies are stored in, the less susceptible you are to incurring a loss of your prized photos.
With the price of memory cards being so low, I now travel with enough memory cards to easily capture my entire trip - often 3 high capacity cards per camera. And my first backup image copy is the original memory card used to capture the photos. The files on the memory cards are as pristine as you can get - there has been no chance of an error (human- or computer-caused) being incurred during data transfer (after the camera is finished with its original data write). Memory cards are also very compact - an important consideration when traveling.
I always travel with a laptop. When possible (generally every night), I upload (via a card reader) any not-previously uploaded photos from the memory cards to my laptop. I typically check/clean the camera sensors while the images are uploading. Immediately after the upload, I usually take advantage of the larger display on the laptop to insure that my results are as expected (that the gear and my techniques are working properly)
After the laptop gets a copy of the day's images, at least one external hard drive gets a copy. I frequently have two external drives with me.
At this point, I have at least three copies of my files. But, if all copies of my images are in one location, I still stand a chance of losing everything due to theft, fire ...
When traveling, I usually have a room somewhere, a vehicle and I consider myself an additional location when not in the room or the car. In addition, I take pre-postage-applied mailers with me on a trip, allowing me to make home a fourth location. And I make use of all of these locations.
I keep filled-and-backed-up memory cards in my pocket and the partially filled memory cards in the cameras I'm carrying until ... Periodically during the trip, I mail the used-to-that-point (not necessarily filled) memory cards home. This move takes lost luggage, theft and many other potential mishaps out of the picture. Of course, mail is not 100% guaranteed, but that is what the other backups are for. Having my mailers pre-addressed and postage applied prior to the trip make this mailing a simple task - typically drop-it-at-the-front-desk easy.
I usually keep the laptop hidden in my room (it is susceptible to theft here - the laptop image is completely backed up prior to the trip). One external hard drive goes out to the car immediately after getting its new pictures for the day. And I usually have a second hard external drive along for another copy to be hidden somewhere.
Your hotel may have a safe available for storing your laptop, external hard drives or memory cards. This can be a good option for one of your data copies.
There are also many online options available for storing your images. Online options take care of both an additional copy and an additional location. I do not take advantage of the online options because of the size of my files relative to the speed of the internet connection I typically have when traveling.
The Original Memory Cards
I alluded to the fact that I keep my original memory cards intact until sometime after I return from my trip. Don't underplay this point - here is an example of where the original cards saved me:
The primary camera I was using in Glacier National Park somehow has its time set incorrectly (I synchronize my camera clocks before leaving on trips - and I have not found a good excuse for my error yet). At the end of each day, I was copying that day's images to my laptop. When I discovered that some of the images (typically sunrise in this case) were missing, I discovered the problem - some images were being tagged with the prior day's date. Fortunately, I was able to go back to my cards and recover the missing files.
Memory cards are cheap - buy lots of them.
There is not one backup strategy that works for everyone, but - having a travel backup policy is important for everyone traveling with a camera.