execution of an ollie depends a lot on how you think about it. Slamming down on the tail
of the skateboard
will yield less result than compressing the body, smacking the tail down a little lighter, and using the decompression of your knees to add lift to the initial pop.
Another misconception about ollies is that the front foot does a lot of work. The job of the front foot is to guide the board. Trying to push out an ollie doesn't really work in these post-suicide bolts days.
Timing is also crucial. If the movements don't flow together the product is pretty durn ugly. You can watch little kids make this mistake all day. Slam down the tail, push with the front foot, back foot flies out, and there is no ollie.
This wu is intended to append the one above by Ads which is just fine the way that it is unless you're anal about these things, like me.