Originally Posted by Roy
...have visible cameras, hang a few LCD screens with the camera image near the entrance so people can see they're being watched.
Originally Posted by acidicboy
I would also check on employees. I used to be part of a retail company and we did have problem with pilferages from within the group.
These are both good advice. I worked in retail loss prevention for a few years, and these were approaches we used. We also used "dummy domes," which were black camera domes that didn't actually contain a camera. They were much cheaper than cameras, but people had no clue they were empty. They deterred theft by making people think they were being watched.
It also helps to have someone in a uniform by the front door, even if that person is completely powerless.
The whole point is create the illusion of surveillance.
That said, some level of shrinkage by theft is pretty much inevitable.