as a natural heelflipper kickflips have eluded me for years but now a days im pretty confident with them & can do them pretty well down gaps, over tall things, etc.. I put my feet in an ollie position with my toes pointing towards the nose & tail (think how mike mo sets up for his switchflips). the ball of my back foot is more towards the center of the tail than right on the edge, and my front foot is slightly bent with my weight on my toes & my heel hovering over my board. I pretty much do an ollie motion, but I look to have half of my front foot slide up the grip, with the toecap going diagonally from the bottom left bolt (im saying this as a goofy-footer) to the top right bolt, to where the axle of the truck pokes out. thats the sorta angle i aim for, and its more of an ollie-then-flick motion as opposed to sliding straight up to the corner of the board. from there its all fundamentals. bend your knees before you pop, keep your shoulders straight, etc.
I will say that when I do them down gaps or off of launch ramps or pyramids, they flip super slow but if im doing lower-popped flat ground ones they're pretty fast. i guess its just relative what you're doing with it. here's some examples of me doing kick flips if that helps any
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