It doesn’t matter what the OS is (I use Windows, OS and Linux daily so I don’t have a perference) — the point is that you must never let anything write to the device if you want to guarantee that you can recover the data from it

However, my wife has a PnS and I’ve had to use REST2514 more than once to recover photos. It’s free and it hasn’t failed me yet.

These file can permanently overwrite the information needed to recover lost files — not just the directory entries but the raw data itself

Although you can tell Spotlight not to index a device, you can only do so after it is plugged in and that preference is forgotten as soon as you unplug it — therefore, it is safer to always use a PC for recovery if you can

You can pre-create empty files with the names that Spotlight/Finder use on a card (.Trashes, .fseventsd, .Spotlight-V100, …) to stop them overwriting data BUT you need to do this everytime you format the card and before you write pictures to it — so this isn’t as useful in practice as it could be

This being said. Recovery percentages average about 60%. And if the damages is physical, well, you can just throw it out in the trash.

As as a rule of thumb I use two guidelines. I spread my pictures across multiple cards. I switch about ever 30 frames or so. I rotate through about 10 small cards every day. That way, I never lose blocks of the day, just smaller portions throughout the day. This also saves money, because it is generally cheaper per gig to buy several smaller cards. I know, it sounds like work, but hey, we changed film.

The second rule is to toss cards after a set amount of time. Generally, bad things happen to older cards. I know, it seems like a waste of money, but technology does wear out with use. Heat damages circuitry, and the storage medium can only be switched between a 1 and 0 so many times. I always tell my friends to get a new computer every 3 years. Most of them don’t listen to me, and invariably I spend a weekend building them a new computer and trying to recover the data that was lost when it crashed. I, usually, keep a card in my work rotation about 6 months. When you think about it, it’s so cheap now that buying new cards every 6 months isn’t bad. Now, this will vary depending on usage levels. I do about 3-4 weddings a week, and use all to half the cards depending on the requirements, and my trigger happiness.

I always repeat this, to everyone, and hour of prevention and a 100$ is worth the three days of labor and the 500$ for a good data recover, oh and the lose of business from word of mouth, etc…

Here’s a link to an open source, free, stable, and easy to use data recovery tool:
http://www.cgsecurity.org/wiki/PhotoRec