Straight from Wikipedia:

There are two schools of thought for basic frontside/backside grinding with Soap Shoes; the first using the leading leg (your right foot if you are goofy and vice versa for regular) as the leg you leap off, landing with your back foot on the rail/ledge/etc. first and subsequently placing your leading foot on moments later. The second technique is to leap off your trailing leg (left foot if goofy etc.) and place your leading foot on the rail/ledge/etc. first following it with your trailing foot moments later. You can also endeavour to land both feet simultaneously on the rail.

There is little advantage from one technique to the other; leading leg first often yeilds more speed but this is at the expense of control, and abandoning a trick if your trail leg fails to lock onto the obstacle proves difficult without risking injury, as your leading leg will be sliding away from you. On the other hand, the trail leg first technique is much more controlled and safer in the event of poor execution, but speed is sacrificed.

The technique used is mostly based on preference due to your natural bias. e.g. a right footed person who is of regular stance(the most common combination) will find it far easier to leap off their left foot and land with their right foot on the rail first using the trailing leg technique outlined above.

I'm regular and usually land on either foot. I'm just pedodextrous like that.

Saying that, though, I've noticed that my right plate is showing a lot more wear than my left... that may say something about my grind style.

i agree surfaced...i HAVE to land my front foot first.....but i think imma teach myself how to do both