The ollie is the basis for almost every skateboard trick. Nine out of ten tricks require an ollie of some sort. If you have the ollie mastered then you are not far from mastering streetstyle. The ollie itself is the act of jumping into the air while keeping your board on your feet. So if you are skating down the sidewalk and all of a sudden an old lady were to fall in front of you and block your path, you would want to ollie over her and keep going on your way.
Step one: Place your front foot in the middle of the board and your back foot on the tip of the tail (or back). This is your preparatory foot placement, it will help you to go higher.
Step two: With your back foot you want to "tap" your tail onto the ground. Do this by smashing your tail downward while jumping up. Once the tail has "popped" off the ground, slide your front foot up from the middle of your board toward the nose (or front). The secret to this trick is timing your "jump" with your "tap," and your "tap" with your "foot slide" - this takes practice, so be patient and you will improve.
Tip: You are jumping off of your back wheels, before your tail actually hits the ground.
Step three: Leveling off. Once airborne, the "foot slide" levels your board out. The "foot slide" is the process of scraping your foot (or more likely, your shoe) upward and forward across the grip tape toward the nose. You do this just after the tail tap and jump. Fact: The tap and the foot slide combined are the ollie's essence, your jump determines its height.
Step four: Land. Tip: A good thing to remember with any trick is what I call the "box." Imagine yourself in an invisible box the size of your skateboard. Always keep your body centered above your board and in this box. I find it helps you to land tricks because a common mistake is to lean too far forward or backward. Thank you and have a nice day, bunghole.