I protect some items by not carrying them with me (travel with checkbook? Never!).

I put my passport in a convenient zipped pocket, because I don't really worry about its being stolen by the TSA. Wallet, credit cards, and small electronic devices I try to make too annoying to get to by burying them--in zipped pocket in purse, purse temporarily in carry on. I also make sure everything's still there before leaving the checkpoint.

I have, and will continue, to insist on keeping my bags in sight if I go through any secondary screening while traveling alone. TSA has been peevish about it when I've done so, but that's too bad.