I have 3 empty houses right around me in kind of a block. After one of them was broken into (local teenagers)the police put me into contact with the owners and realtors and now I keep an eye on those places.
I walk around them a couple times per week and look for obvious signs of damage or break in. I also shine a light around about one night per week. I’ve got a remote for all the outside floodlights at the house behind me. It lights the place up like a prison yard.
What I’m not going to do is confront someone over an empty house. If I see them in the process of breaking in or snooping around I might give a shout to scare them off but I’m not going to try to hold them. If someone is inside I’m just going to stay out of sight and call the police to deal with it.