The only way to keep such safe is to keep it off phones, PCs that are connected to the internet. Nothing is entirely safe, even printed material in a vault.
But that's not why I replied. Prey is more about finding your lost device and maybe wiping it.
If you forgot to install Prey or another LoJack like there is always Plan B. Link follows,
I read a message on another forum where a user was recommending "Prey". I looked into it, but as I have never heard of it before I was wondering just how reliable this product is. Also, just how safe is my privacy? Can I be sure my financial information and other such personal data is safe from prying eyes???