Why be all worked up over shopping centre car parks ehh? I'm not going to tell anyone what is the correct way because there is none - you own a car, you drive it out, there is an obvious risk no matter how good a driver you are = FACT!
That is what insurance is for.
I used to be full paranoid about being in a public car park or even on the street... but I soon realized that if it's going to happen, then there's nothing you can do to stop it.
Shopping Centre advice:
* Park between poles
* Park between SMALL cars (Charades, Minis, Civics etc)
* Park away from trolley collection points
* Park away from any main entries (everyone fights for these spots)
* Park on the roof (most remote place of the SC)
* Park away from the lift/s
* Park away from stupidly large vehicles (vans, 4WD, delivery trucks)
* Park in spaces that are against the wall which are parralel
As for the $500 box for shopping... only if you are going to use it as a daily driver to save $$$ on fuel as well. Having one just to go to public domains is not very viable, better off getting a kickass bike with a storage bag in the back for your groceries.