When you approach your car, walk around it. Look carefully to see if it has been tampered with. Me? I look down at the tires to see if someone has punched a hole in one since a quick way to catch you is to ensure you have a flat tire. Sneaky thieves will punch 2 tires so you *really* cannot get away. And *really* sneaky people will not punch your tires–they’ll put 2 caltrops down right under the tire so everything looks fine until you start to drive away–then “Bang!” and you’re stuck.
So look at things first.