A UPS delivery truck driver once told me that it's safer to back into a parking space, so that you can pull out forward, than vice versa.

I think I can see the logic of this. You're more likely to encounter a pedestrian or another vehicle unexpectedly crossing your path while you're leaving a parking space than while you're entering it, so that's when you most need to see clearly where you're going.

Having said that, I have to admit that I haven't taken his advice, simply because it's harder that way.