Seeing as this thread was revitalized, I'll ask about popping out of boardslides (front or back) in the middle of a rail. That shit baffles me.
I think the object of that trick is to get your board soooo near vertical while turning out/hopping away from the ledge that the edge of your board is the only surface of your board gliding against the rail durring that split second of popping out, so that when gravity pulls you and your board down, your board sorta slides down the side of the rail instead of locking up into a willie grind or whatever
(see fig. 1)
that make sense?
I've found that I can only do this trick well on tall things. If I do it on something smaller, I can land and roll away, but my tail will hit the ground before my board's even off the rail, it's super weird.
fig.1 (kickflip front board pop-over fakie)
I'd say a decent warm-up for these tricks would be like a planter box ledge or rail, where you have to pop out to avoid a perpendicular rail.