Place property in the trunk. Always lock your car when you leave it. A lot of students study in the comfort of their vehicle. Never feel that you could be calling the police on an innocent person. If everything is legit the person will be on their way.
Crime prevention is a community effort.
The vehicle you save may be your own. The answer to these questions is largely subjective. If something out of the ordinary takes place in your office, you need to articulate it so the officer knows what has taken place. If someone is hanging around your office for a long time, this may be suspicious. If a person is walking through the parking lot looking into vehicles, this is suspicious.