Imagine your dream vacation: two weeks, exotic locales, amazing photo ops. Or maybe it's your first born: weekly belly photos, baby showers, the big day, little baby steps. It could be an entire year of events and milestones. These days you can easily take thousands of photos on big memory cards before filling them up. I mean, it's just so convenient right? Only one problem, imagine how you would feel if that one card suddenly failed. There's a chance you could recover some of the pictures, but still. And it does happen - just like it did to a friend of ours who had a dream anniversary vacation to Hawaii. Trust me, it's not a good feeling. So what can you do? Don't keep all your eggs in one basket - shoot with smaller memory cards!
I fell into this habit when I used to shoot weddings. It's bad enough if you lose your personal photos, but it's a whole other thing to lose someone else's memories that you're in charge of. Instead of shooting on the biggest memory card, I decided to shoot with several smaller cards. This way if something happened with one card, the whole day (6-8 hours of shooting) would not be lost. For weddings, we would each fill up a set of 10 - 4GB memory cards. We shot in RAW and since our camera's RAW files are crazy big, the images take up lots of space. That being said, you could still fit a high (risky) number of JPG images on that same 4GB card. So for JPG shooting I would recommend 2GB or smaller cards or you could deliberately switch out cards to keep from taking all pics on the same card. We do that when we're shooting in JPG on our 5D Mark II cameras with the 4GB cards.
It should be noted that memory cards continue to get bigger and bigger since I first wrote this post. My advice is to shoot with the smallest cards you can buy, depending on the file sizes of your camera.
Of course, shooting with smaller memory cards means having more to keep up with (and lose!) To keep up with all our cards we use Think Tank's Pixel Pockets. I LOVE my Pixel Pocket except I don't trust that plastic strap to hang it on. No way Jose, that baby stays in my camera bag.
Pixel Pockets are awesome! There are 3 different sizes / kinds to choose from. My husband and I both have a blue 10 card Pixel Pocket. There's also a 6 card holder and then the Pixel Wee (the cute red one) holds 6 cards. The blue ones are actually designed to hold compact flash cards (out of their little plastic case.) Only the red Pixel Wee holds SD cards (and only 3 of them.) However if you keep your SD cards in their plastic case, they fit in the compact flash spots perfectly.
Remember, digital cameras are amazing but don't shoot all your pictures on the same card! Shoot over several cards during vacation / big events and back up often when possible. If you are using just your iPhone then be sure to have it set up to back up to the cloud. You'll be glad you did!