Also, I walk my dogs during the day and I have been trying to take them on longer and longer walks that cover more of the neighborhood, but it is also a matter of being in the right place at the right time.
Those of us that are here during the day can always take an extra minute to drive a more circuitous route through the neighborhood as we come and go to keep an eye out for anything suspicious. Again, I try and do this as I come and go.
Other than that I am really only able to try and keep an eye on things near my house at other times. I think that there are enough people at home during the day that we can catch these people by just being a little more observant.