Very visible to others
You want to make sure that when you are choosing a parking lot to park your vehicle that it is very visible. In case something should happen, you want other people to be able to see and offer help if necessary. You never want to park in a parking lot that is off in some remote location where no one can see you. If something were to happen, then no one would even know that you were in any kind of trouble.
Try to park during the day
There is only so much you can do about this one. If you have to park at night, then you have to park at night. However, if you can choose whether or not to park during the day or the night, then I would highly suggest parking during the day. It is pretty well known that any type of criminal activity is usually significantly less during the day light hours than it is during the night hours.
If it is at night, make sure it is well lit
If you have to park at night, then make sure the parking lot that you choose is well lit. You want to make sure there are plenty of lights in the parking lot and that everything can be seen very well. You do not want to park somewhere where you cannot see in certain areas where someone who is looking to do you any kind of harm could be waiting.
In a parking garage, choose lowest level
If you have to park inside of a parking garage, then you should park in the lowest level possible. This is because the lower levels are more likely to have other vehicles driving through them. You do not want to park all the way up top where there are less people around and more opportunity for someone to harm you or your vehicle.
The more people, the better
You want to make sure that the parking lot you choose to park in is heavily trafficked by other people as well. You never want to park somewhere where there are not very many people going in and out. The more people that are there, the less likely someone is to try and harm you. And if something should happen, you are more likely to get help if there are plenty of people around.