The oldschool kickflip, predecessor of the ollie kickflip, was one of the earliest skateboarding "flip tricks", and came even before the ollie. Today the oldshool kickflip is almost entirely forgotten, and when it is done, the performer is swarmed by an angry horde of young children with skateboards who want to tell you that "Thats not how you do a kickflip, Chad Muska told me so in the magazine!". Pay no heed to these protests, for you know perfectly well that its a perfectly fine trick.
You will probably want to master this trick standing still before doing it at speed, because no matter what the swarm of children say, its not easier than a kickflip, and you can get hurt. Stand on the board with both feet relatively near the center of the board, and hunch down low, ready to spring, leaping slightly to the side that the board will be spinning towards, as the oldschool kickflip is also called a barrel roll, due to its tendency to roll over to the side as it flips. When your ready to do it, you should concentrate on completeing all the movements in one smooth motion. Start your leap as you move your rear foot off the board, then underneath it, hooking your toe under the edge, ready to whip spinning into space. When your legs are almost totally extended and you have plenty of upward momentum, you should lift your front foot clear of the board as you flick it into a spin with your toes and suck that leg up under you. This is the fun part of the trick, where you dangle in space over the board for a suspiciously long time. Wait with your legs lifted until you see the black, griptaped side of the board coming around like a sunset viewed from space. Extend your legs down towards the dark side of the moon to catch the board mid-rotation and slap it back to terra firma with an earthly crack. Absorb the impact with your knees, not your back, much like heavy lifting, and roll away, quickly if possible, as the angry skateboarding children are on there way.