When I bring this subject up during class on how and where to park your motorycycle, this is what I tell them.
Your riding strategy on the road is based on that motorcycles are very difficult to spot due to it's small size. The parking lot is no different, and actually even worse because half of the people are backing up. Also, most of them don't even back up properly as far as using the proper head over the shoulder technique, and relying too much on their mirrors while talking on their cell phones.
My roomate is a valet attendant for one of the major casino's and I asked him one day why do valet's always back the guest's vehicles into the parking space? His answer, is because there is less chances for conflict when pulling out of the parking space.
With that in mind, in the .01 percent chance that you find me parking in a parking lot, I will park my bike towards the rear of the stall rather than the middle or front. I will take my chances that someone will see that the spot is occupied while driving forward.
If I place my bike towards the front of the stall to let people know that the space is occuppied, I'm leaving my bike vulnerable for the idiots who may not see the bike because they are careless or have the inability to back up properly. What does someone usually do when they back up and see an open space behind them? Chances are they will utilize that open space by going into it, making it easier for them to back up. Because of the bike being so small and low to the ground, they may not see your bike. You could possibly save it from being hit if it's toward the back, leave some buffer zone just in case.
You should always try to have the bike facing outwards. Meaning, back the bike in. One it makes it easier to pull out, and most importantly, your bike is much more visible from the front vs the rear. The Windscreen and fairings, if you have one will make the bike appear much larger.
Just like crashes, parking your bike so that it doesn't get knocked down can be prevented in most cases.
Use common sense when parking, especially if you are going to park in an area that is not officially designated as parking. Allow plenty of room for pedestrian traffic and don't block the flow of foot traffic. If parked next to a disable stall, make sure that you leave enough room so that it is van/ramped accessible.
Just this Sunday, I stopped at a sportsbar to watch some football and eat breakfast. I pulled my bike right up onto the side of the entry way of the restaraunt, which was plenty wide. When I walked in, I noticed a cop eating and I happen to sit a couple of tables next to him. He left before me and he walked right past my bike. Obviously, if he had a problem on how or where I parked my bike, I'm sure he would have let me known.
Like I said, common sense.