Tracy is going on a backpack trip in France and Spain soon and she wants to know what size memory cards and how many of them she should bring for taking pictures. Leo says that he's often torn between the convenience of one large card and the security of several smaller ones. But Leo says having enough cards so she doesn't have to erase them is a good idea. If her camera can upload images to her phone for a backup, so much the better. The key, though, is to swap out cards often and offload them to a computer or the cloud. Leo doesn't delete the images off his card either. Then he can use the cards as a backup to those that have already been offloaded.
What about video? Leo says video will run about a gigabyte an hour. So a 32 GB card will give her a lot of video. She should shoot short, six to ten second clips that she can mix with stills. It's plenty to trigger her memory. The good news is that microSD cards are cheap and likely about 5-10 cards at 32 or 64GB would be more than enough.
Chris Marquardt says to treat cards like film. If she would've brought 20 rolls of film, then bring 20 cards.