In 1978, Alan Gelfand, who was given his nickname "Ollie" by Scott Goodman, learned to perform no-handed aerials in bowls and pools using a gentle raising of the nose and scooping motion to keep the board with the feet. There are numerous references to Alan Gelfand's Ollie with most notably pictures in the 1970s skateboarding magazine "Skateboarder".
To get higher ollies, I would suggesting resting your back foot on the very end of the tail and the front foot in the middle of the deck to allow for more slide. Popping as hard as you can and catching your board in the groove of the nose with you ankle practically resting in the groove will level the board out in the air. after this initial movement slide you feet back to the bolts on the tail and nose to ensure a clean landing.